PART I.

GOETHE'S

THEORY OF COLOURS;

TRANSLATED FROM THE GERMAN:

WITH NOTES BY

CHARLES LOCK EASTLAKE, R.A., F.R.S.

"Cicero varietatem propriè in coloribus nasci, hinc in

alienum migrare existimavit. Certè non alibi natura

copiosius aut majore lasciviâ opes suas commendavit.

Metalla, gemmas, marmora, flores, astra, omnia denique quæ

progenuit suis etiam coloribus distinxit; ut venia debeatur

si quis in tam numerosâ rerum sylvâ caligaverit."

CELIO CALCAGNINI.

LONDON:

JOHN MURRAY, ALBEMARLE STREET.

1840

TO

JEREMIAH HARMAN, Esq.

Dear Sir,

I dedicate to you the following translation as a testimony

of my sincere gratitude and respect; in doing so, I but

follow the example of Portius, an Italian writer, who

inscribed his translation of Aristotle's Treatise on Colours

to one of the Medici.

I have the honour to be,

Dear Sir,

Your most obliged and obedient Servant,

C. L. EASTLAKE.

THE TRANSLATOR'S PREFACE.

English writers who have spoken of Goethe's "Doctrine of Colours,"[1]

have generally confined their remarks to those parts of the work in

which he has undertaken to account for the colours of the prismatic

spectrum, and of refraction altogether, on principles different

from the received theory of Newton. The less questionable merits

of the treatise consisting of a well-arranged mass of observations

and experiments, many of which are important and interesting, have

thus been in a great measure overlooked. The translator, aware of

the opposition which the theoretical views alluded to have met with,

intended at first to make a selection of such of the experiments as

seem more directly applicable to the theory and practice of painting.

Finding, however, that the alterations this would have involved would

have been incompatible with a clear and connected view of the author's

statements, he preferred giving the theory itself entire, reflecting,

at the same time, that some scientific readers may be curious to hear

the author speak for himself even on the points at issue.

In reviewing the history and progress of his opinions and researches,

Goethe tells us that he first submitted his views to the public

in two short essays entitled "Contributions to Optics." Among the

circumstances which he supposes were unfavourable to him on that

occasion, he mentions the choice of his title, observing that by a

reference to optics he must have appeared to make pretensions to a

knowledge of mathematics, a science with which he admits he was very

imperfectly acquainted. Another cause to which he attributes the severe

treatment he experienced, was his having ventured so openly to question

the truth of the established theory: but this last provocation could

not be owing to mere inadvertence on his part; indeed the larger work,

in which he alludes to these circumstances, is still more remarkable

for the violence of his objections to the Newtonian doctrine.

There can be no doubt, however, that much of the opposition Goethe met

with was to be attributed to the manner as well as to the substance

of his statements. Had he contented himself with merely detailing his

experiments and showing their application to the laws of chromatic

harmony, leaving it to others to reconcile them as they could with the

pre-established system, or even to doubt in consequence, the truth of

some of the Newtonian conclusions, he would have enjoyed the credit

he deserved for the accuracy and the utility of his investigations.

As it was, the uncompromising expression of his convictions only

exposed him to the resentment or silent neglect of a great portion

of the scientific world, so that for a time he could not even obtain

a fair hearing for the less objectionable or rather highly valuable

communications contained in his book. A specimen of his manner of

alluding to the Newtonian theory will be seen in the preface.

It was quite natural that this spirit should call forth a somewhat

vindictive feeling, and with it not a little uncandid as well as

unsparing criticism. "The Doctrine of Colours" met with this reception

in Germany long before it was noticed in England, where a milder and

fairer treatment could hardly be expected, especially at a time when,

owing perhaps to the limited intercourse with the continent, German

literature was far less popular than it is at present. This last fact,

it is true, can be of little importance in the present instance,

for although the change of opinion with regard to the genius of an

enlightened nation must be acknowledged to be beneficial, it is to be

hoped there is no fashion in science, and the translator begs to state

once for all, that in advocating the neglected merits of the "Doctrine

of Colours," he is far from undertaking to defend its imputed errors.

Sufficient time has, however, now elapsed since the publication of this

work (in 1810) to allow a calmer and more candid examination of its

claims. In this more pleasing task Germany has again for some time led

the way, and many scientific investigators have followed up the hints

and observations of Goethe with a due acknowledgment of the acuteness

of his views.[2]

It may require more magnanimity in English scientific readers to do

justice to the merits of one who was so open and, in many respects, it

is believed, so mistaken an opponent of Newton; but it must be admitted

that the statements of Goethe contain more useful principles in all

that relates to harmony of colour than any that have been derived from

the established doctrine. It is no derogation of the more important

truths of the Newtonian theory to say, that the views it contains

seldom appear in a form calculated for direct application to the arts.

The principle of contrast, so universally exhibited in nature, so

apparent in the action and re-action of the eye itself, is scarcely

hinted at. The equal pretensions of seven colours, as such, and the

fanciful analogies which their assumed proportions could suggest, have

rarely found favour with the votaries of taste,--indeed they have

long been abandoned even by scientific authorities.[3] And here the

translator stops: he is quite aware that the defects which make the

Newtonian theory so little available for æsthetic application, are

far from invalidating its more important conclusions in the opinion

of most scientific men. In carefully abstaining therefore from any

comparison between the two theories in these latter respects, he may

still be permitted to advocate the clearness and fulness of Goethe's

experiments. The German philosopher reduces the colours to their

origin and simplest elements; he sees and constantly bears in mind, and

sometimes ably elucidates, the phenomena of contrast and gradation,

two principles which may be said to make up the artist's world, and to

constitute the chief elements of beauty. These hints occur mostly in

what may be called the scientific part of the work. On the other hand,

in the portion expressly devoted to the æsthetic application of the

doctrine, the author seems to have made but an inadequate use of his

own principles.

In that part of the chapter on chemical colours which relates to the

colours of plants and animals, the same genius and originality which

are displayed in the Essays on Morphology, and which have secured

to Goethe undisputed rank among the investigators of nature, are

frequently apparent.

But one of the most interesting features of Goethe's theory, although

it cannot be a recommendation in a scientific point of view, is, that

it contains, undoubtedly with very great improvements, the general

doctrine of the ancients and of the Italians at the revival of letters.

The translator has endeavoured, in some notes, to point out the

connexion between this theory and the practice of the Italian painters.

The "Doctrine of Colours," as first published in 1810, consists of

two volumes in 8vo., and sixteen plates, with descriptions, in 4to.

It is divided into three parts, a didactic, a controversial, and an

historical part; the present translation is confined to the first of

these, with such extracts from the other two as seemed necessary,

in fairness to the author, to explain some of his statements. The

polemical and historical parts are frequently alluded to in the

preface and elsewhere in the present work, but it has not been thought

advisable to omit these allusions. No alterations whatever seem to

have been made by Goethe in the didactic portion in later editions,

but he subsequently wrote an additional chapter on entoptic colours,

expressing his wish that it might be inserted in the theory itself at

a particular place which he points out. The form of this additional

essay is, however, very different from that of the rest of the work,

and the translator has therefore merely given some extracts from it in

the appendix. The polemical portion has been more than once omitted in

later editions.

In the two first parts the author's statements are arranged

numerically, in the style of Bacon's Natural History. This, we are

told, was for the convenience of reference; but many passages are

thus separately numbered which hardly seem to have required it. The

same arrangement is, however, strictly followed in the translation to

facilitate a comparison with the original where it may be desired; and

here the translator observes, that although he has sometimes permitted

himself to make slight alterations, in order to avoid unnecessary

repetition, or to make the author's meaning clearer, he feels that an

apology may rather be expected from him for having omitted so little.

He was scrupulous on this point, having once determined to translate

the whole treatise, partly, as before stated, from a wish to deal

fairly with a controversial writer, and partly because many passages,

not directly bearing on the scientific views, are still characteristic

of Goethe. The observations which the translator has ventured to add

are inserted in the appendix: these observations are chiefly confined

to such of the author's opinions and conclusions as have direct

reference to the arts; they seldom interfere with the scientific

propositions, even where these have been considered most vulnerable.

[1] "Farbenlehre"--in the present translation generally rendered

"Theory of Colours."

[2] Sixteen years after the appearance of the Farbenlehre, Dr.

Johannes Müller devoted a portion of his work, "Zur vergleichenden

Physiologie des Gesichtssinnes des Menschen und der Thiere," to the

critical examination of Goethe's theory. In his introductory remarks he

expresses himself as follows--"For my own part I readily acknowledge

that I have been greatly indebted to Goethe's treatise, and can truly

say that without having studied it for some years in connexion with the

actual phenomena, the present work would hardly have been undertaken.

I have no hesitation in confessing more particularly that I have full

faith in Goethe's statements, where they are merely descriptive of

the phenomena, and where the author does not enter into explanations

involving a decision on the great points of controversy." The names of

Hegel, Schelling, Seebeck, Steffens, may also be mentioned, and many

others might be added, as authorities more or less favourable to the

Farbenlehre.

[3] "When Newton attempted to reckon up the rays of light decomposed

by the prism," says Sir John Leslie, "and ventured to assign the

famous number _seven_, he was apparently influenced by some lurking

disposition towards mysticism. If any unprejudiced person will fairly

repeat the experiment, he must soon be convinced that the various

coloured spaces which paint the spectrum slide into each other by

indefinite shadings: he may name four or five principal colours, but

the subordinate spaces are evidently so multiplied as to be incapable

of enumeration. The same illustrious mathematician, we can hardly

doubt, was betrayed by a passion for analogy, when he imagined that the

primary colours are distributed over the spectrum after the proportions

of the diatonic scale of music, since those intermediate spaces have

really no precise and defined limits."--_Treatises on Various Subjects

of Natural and Chemical Philosophy_, p. 59.

PREFACE TO THE FIRST EDITION OF 1810.

It may naturally be asked whether, in proposing to treat of colours,

light itself should not first engage our attention: to this we briefly

and frankly answer that since so much has already been said on the

subject of light, it can hardly be desirable to multiply repetitions by

again going over the same ground.

Indeed, strictly speaking, it is useless to attempt to express the

nature of a thing abstractedly. Effects we can perceive, and a complete

history of those effects would, in fact, sufficiently define the

nature of the thing itself. We should try in vain to describe a man's

character, but let his acts be collected and an idea of the character

will be presented to us.

The colours are acts of light; its active and passive modifications:

thus considered we may expect from them some explanation respecting

light itself. Colours and light, it is true, stand in the most intimate

relation to each other, but we should think of both as belonging to

nature as a whole, for it is nature as a whole which manifests itself

by their means in an especial manner to the sense of sight.

The completeness of nature displays itself to another sense in a

similar way. Let the eye be closed, let the sense of hearing be

excited, and from the lightest breath to the wildest din, from the

simplest sound to the highest harmony, from the most vehement and

impassioned cry to the gentlest word of reason, still it is Nature that

speaks and manifests her presence, her power, her pervading life and

the vastness of her relations; so that a blind man to whom the infinite

visible is denied, can still comprehend an infinite vitality by means

of another organ.

And thus as we descend the scale of being, Nature speaks to other

senses--to known, misunderstood, and unknown senses: so speaks she with

herself and to us in a thousand modes. To the attentive observer she

is nowhere dead nor silent; she has even a secret agent in inflexible

matter, in a metal, the smallest portions of which tell us what

is passing in the entire mass. However manifold, complicated, and

unintelligible this language may often seem to us, yet its elements

remain ever the same. With light poise and counterpoise, Nature

oscillates within her prescribed limits, yet thus arise all the

varieties and conditions of the phenomena which are presented to us in

space and time.

Infinitely various are the means by which we become acquainted with

these general movements and tendencies: now as a simple repulsion and

attraction, now as an upsparkling and vanishing light, as undulation

in the air, as commotion in matter, as oxydation and de-oxydation; but

always, uniting or separating, the great purpose is found to be to

excite and promote existence in some form or other.

The observers of nature finding, however, that this poise and

counterpoise are respectively unequal in effect, have endeavoured to

represent such a relation in terms. They have everywhere remarked and

spoken of a greater and lesser principle, an action and resistance,

a doing and suffering, an advancing and retiring, a violent and

moderating power; and thus a symbolical language has arisen, which,

from its close analogy, may be employed as equivalent to a direct and

appropriate terminology.

To apply these designations, this language of Nature to the subject

we have undertaken: to enrich and amplify this language by means of

the theory of colours and the variety of their phenomena, and thus

facilitate the communication of higher theoretical views, was the

principal aim of the present treatise.

The work itself is divided into three parts. The first contains the

outline of a theory of colours. In this, the innumerable cases which

present themselves to the observer are collected under certain leading

phenomena, according to an arrangement which will be explained in

the Introduction; and here it may be remarked, that although we have

adhered throughout to experiment, and throughout considered it as our

basis, yet the theoretical views which led to the arrangement alluded

to, could not but be stated. It is sometimes unreasonably required by

persons who do not even themselves attend to such a condition, that

experimental information should be submitted without any connecting

theory to the reader or scholar, who is himself to form his conclusions

as he may list. Surely the mere inspection of a subject can profit us

but little. Every act of seeing leads to consideration, consideration

to reflection, reflection to combination, and thus it may be said that

in every attentive look on nature we already theorise. But in order to

guard against the possible abuse of this abstract view, in order that

the practical deductions we look to should be really useful, we should

theorise without forgetting that we are so doing, we should theorise

with mental self-possession, and, to use a bold word, with irony.

In the second part[1] we examine the Newtonian theory; a theory which

by its ascendancy and consideration has hitherto impeded a free inquiry

into the phenomena of colours. We combat that hypothesis, for although

it is no longer found available, it still retains a traditional

authority in the world. Its real relations to its subject will require

to be plainly pointed out; the old errors must be cleared away, if the

theory of colours is not still to remain in the rear of so many other

better investigated departments of natural science. Since, however,

this second part of our work may appear somewhat dry as regards its

matter, and perhaps too vehement and excited in its manner, we may here

be permitted to introduce a sort of allegory in a lighter style, as a

prelude to that graver portion, and as some excuse for the earnestness

alluded to.

We compare the Newtonian theory of colours to an old castle, which

was at first constructed by its architect with youthful precipitation;

it was, however, gradually enlarged and equipped by him according

to the exigencies of time and circumstances, and moreover was still

further fortified and secured in consequence of feuds and hostile

demonstrations.

The same system was pursued by his successors and heirs: their

increased wants within, the harassing vigilance of their opponents

without, and various accidents compelled them in some places to build

near, in others in connexion with the fabric, and thus to extend the

original plan.

It became necessary to connect all these incongruous parts and

additions by the strangest galleries, halls and passages. All damages,

whether inflicted by the hand of the enemy or the power of time, were

quickly made good. As occasion required, they deepened the moats,

raised the walls, and took care there should be no lack of towers,

battlements, and embrasures. This care and these exertions gave rise

to a prejudice in favour of the great importance of the fortress,

and still upheld that prejudice, although the arts of building and

fortification were by this time very much advanced, and people had

learnt to construct much better dwellings and defences in other cases.

But the old castle was chiefly held in honour because it had never

been taken, because it had repulsed so many assaults, had baffled so

many hostile operations, and had always preserved its virgin renown.

This renown, this influence lasts even now: it occurs to no one that

the old castle is become uninhabitable. Its great duration, its costly

construction, are still constantly spoken of. Pilgrims wend their

way to it; hasty sketches of it are shown in all schools, and it is

thus recommended to the reverence of susceptible youth. Meanwhile,

the building itself is already abandoned; its only inmates are a few

invalids, who in simple seriousness imagine that they are prepared for

war.

Thus there is no question here respecting a tedious siege or a

doubtful war; so far from it we find this eighth wonder of the world

already nodding to its fall as a deserted piece of antiquity, and

begin at once, without further ceremony, to dismantle it from gable

and roof downwards; that the sun may at last shine into the old nest

of rats and owls, and exhibit to the eye of the wondering traveller

that labyrinthine, incongruous style of building, with its scanty,

make-shift contrivances, the result of accident and emergency, its

intentional artifice and clumsy repairs. Such an inspection will,

however, only be possible when wall after wall, arch after arch, is

demolished, the rubbish being at once cleared away as well as it can be.

To effect this, and to level the site where it is possible to do

so, to arrange the materials thus acquired, so that they can be

hereafter again employed for a new building, is the arduous duty

we have undertaken in this Second Part. Should we succeed, by a

cheerful application of all possible ability and dexterity, in razing

this Bastille, and in gaining a free space, it is thus by no means

intended at once to cover the site again and to encumber it with a new

structure; we propose rather to make use of this area for the purpose

of passing in review a pleasing and varied series of illustrative

figures.

The third part is thus devoted to the historical account of early

inquirers and investigators. As we before expressed the opinion that

the history of an individual displays his character, so it may here be

well affirmed that the history of science is science itself. We cannot

clearly be aware of what we possess till we have the means of knowing

what others possessed before us. We cannot really and honestly rejoice

in the advantages of our own time if we know not how to appreciate

the advantages of former periods. But it was impossible to write, or

even to prepare the way for a history of the theory of colours while

the Newtonian theory existed; for no aristocratic presumption has ever

looked down on those who were not of its order, with such intolerable

arrogance as that betrayed by the Newtonian school in deciding on

all that had been done in earlier times and all that was done around

it. With disgust and indignation we find Priestley, in his History

of Optics, like many before and after him, dating the success of all

researches into the world of colours from the epoch of a decomposed ray

of light, or what pretended to be so; looking down with a supercilious

air on the ancient and less modern inquirers, who, after all, had

proceeded quietly in the right road, and who have transmitted to us

observations and thoughts in detail which we can neither arrange better

nor conceive more justly.

We have a right to expect from one who proposes to give the history of

any science, that he inform us how the phenomena of which it treats

were gradually known, and what was imagined, conjectured, assumed,

or thought respecting them. To state all this in due connexion is by

no means an easy task; need we say that to write a history at all is

always a hazardous affair; with the most honest intention there is

always a danger of being dishonest; for in such an undertaking, a

writer tacitly announces at the outset that he means to place some

things in light, others in shade. The author has, nevertheless, long

derived pleasure from the prosecution of his task: but as it is the

intention only that presents itself to the mind as a whole, while the

execution is generally accomplished portion by portion, he is compelled

to admit that instead of a history he furnishes only materials for

one. These materials consist in translations, extracts, original and

borrowed comments, hints, and notes; a collection, in short, which, if

not answering all that is required, has at least the merit of having

been made with earnestness and interest. Lastly, such materials,--not

altogether untouched it is true, but still not exhausted,--may be more

satisfactory to the reflecting reader in the state in which they are,

as he can easily combine them according to his own judgment.

This third part, containing the history of the science, does not,

however, thus conclude the subject: a fourth supplementary portion[2]

is added. This contains a recapitulation or revision; with a view

to which, chiefly, the paragraphs are headed numerically. In the

execution of a work of this kind some things may be forgotten, some

are of necessity omitted, so as not to distract the attention, some

can only be arrived at as corollaries, and others may require to be

exemplified and verified: on all these accounts, postscripts, additions

and corrections are indispensable. This part contains, besides, some

detached essays; for example, that on the atmospheric colours; for as

these are introduced in the theory itself without any classification,

they are here presented to the mind's eye at one view. Again, if this

essay invites the reader to consult Nature herself, another is intended

to recommend the artificial aids of science by circumstantially

describing the apparatus which will in future be necessary to assist

researches into the theory of colours.

In conclusion, it only remains to speak of the plates which are added

at the end of the work;[3] and here we confess we are reminded of that

incompleteness and imperfection which the present undertaking has,

in common with all others of its class; for as a good play can be in

fact only half transmitted to writing, a great part of its effect

depending on the scene, the personal qualities of the actor, the powers

of his voice, the peculiarities of his gestures, and even the spirit

and favourable humour of the spectators; so it is, in a still greater

degree, with a book which treats of the appearances of nature. To be

enjoyed, to be turned to account, Nature herself must be present to

the reader, either really, or by the help of a lively imagination.

Indeed, the author should in such cases communicate his observations

orally, exhibiting the phenomena he describes--as a text, in the

first instance,--partly as they appear to us unsought, partly as they

may be presented by contrivance to serve in particular illustration.

Explanation and description could not then fail to produce a lively

impression.

The plates which generally accompany works like the present are thus

a most inadequate substitute for all this; a physical phenomenon

exhibiting its effects on all sides is not to be arrested in lines

nor denoted by a section. No one ever dreams of explaining chemical

experiments with figures; yet it is customary in physical researches

nearly allied to these, because the object is thus found to be in

some degree answered. In many cases, however, such diagrams represent

mere notions; they are symbolical resources, hieroglyphic modes of

communication, which by degrees assume the place of the phenomena and

of Nature herself, and thus rather hinder than promote true knowledge.

In the present instance we could not dispense with plates, but we have

endeavoured so to construct them that they may be confidently referred

to for the explanation of the didactic and polemical portions. Some of

these may even be considered as forming part of the apparatus before

mentioned.

We now therefore refer the reader to the work itself; first, only

repeating a request which many an author has already made in vain, and

which the modern German reader, especially, so seldom grants:--

Si quid novisti rectius istis

Candidus imperti; si non, his utere mecum.

[1] The Polemical part.

[2] This preface must have been written before the work was finished,

for at the conclusion of the historical part there is only an apology

for the non-appearance of the supplement here alluded to.

[3] In the present translation the necessary plates accompany the

text.

CONTENTS

Introduction xxxvii

PART I.

PHYSIOLOGICAL COLOURS.

I. Effects of Light and Darkness on the Eye

II. Effects of Black and White Objects on the Eye

III. Grey Surfaces and Objects

IV. Dazzling Colourless Objects

V. Coloured Objects

VI. Coloured Shadows

VII. Faint Lights

VIII. Subjective Halos

Pathological Colours--Appendix

PART II.

PHYSICAL COLOURS.

IX. Dioptrical Colours

X. Dioptrical Colours of the First Class

XI. Dioptrical Colours of the Second Class--Refraction

Subjective Experiments

XII. Refraction without the Appearance of Colour

XIII. Conditions of the Appearance of Colour

XIV. Conditions under which the Appearance of Colour increases

XV. Explanation of the foregoing Phenomena

XVI. Decrease of the Appearance of Colour

XVII. Grey Objects displaced by Refraction

XVIII. Coloured Objects displaced by Refraction

XIX. Achromatism and Hyperchromatism

XX. Advantages of Subjective Experiments--

Transition to the Objective

Objective Experiments

XXI. Refraction without the Appearance of Colour

XXII. Conditions of the Appearance of Colour

XXIII. Conditions of the Increase of Colour

XXIV. Explanation of the foregoing Phenomena

XXV. Decrease of the Appearance of Colour

XXVI. Grey Objects

XXVII. Coloured Objects

XXVIII. Achromatism and Hyperchromatism

XXIX. Combination of Subjective and Objective Experiments

XXX. Transition

XXXI. Catoptrical Colours

XXXII. Paroptical Colours

XXXIII. Epoptical Colours

PART III.

CHEMICAL COLOURS.

XXXIV. Chemical Contrast

XXXV. White

XXXVI. Black

XXXVII. First Excitation of Colour

XXXVIII. Augmentation of Colour

XXXIX. Culmination

XL. Fluctuation

XLI. Passage through the Whole Scale

XLII. Inversion

XLIII. Fixation

XLIV. Intermixture, Real

XLV. Intermixture, Apparent

XLVI. Communication, Actual

XLVII. Communication, Apparent

XLVIII. Extraction

XLIX. Nomenclature

L. Minerals

LI. Plants

LII. Worms, Insects, Fishes

LIII. Birds

LIV. Mammalia and Human Beings

LV. Physical and Chemical Effects of the Transmission

of Light through Coloured Mediums

LVI. Chemical Effect in Dioptrical Achromatism

PART IV.

GENERAL CHARACTERISTICS.

The Facility with which Colour appears

The Definite Nature of Colour

Combination of the Two Principles

Augmentation to Red

Junction of the Two Augmented Extremes

Completeness the Result of Variety in Colour

Harmony of the Complete State

Facility with which Colour may be made to tend either to

the Plus or Minus side

Evanescence of Colour

Permanence of Colour

PART V.

RELATION TO OTHER PURSUITS.

Relation to Philosophy

Relation to Mathematics

Relation to the Technical Operations of the Dyer

Relation to Physiology and Pathology

Relation to Natural History

Relation to General Physics

Relation to the Theory of Music

Concluding Observations on Terminology

PART VI.

EFFECT OF COLOUR WITH REFERENCE TO MORAL ASSOCIATIONS.

Yellow

Red-Yellow

Yellow-Red

Blue

Red-Blue

Blue-Red

Red

Green

Completeness and Harmony

Characteristic Combinations

Yellow and Blue

Yellow and Red

Blue and Red

Yellow-Red and Blue-Red

Combinations Non-Characteristic

Relation of the Combinations to Light and Dark

Considerations derived from the Evidence of Experience and History

Æsthetic Influence

Chiaro-Scuro

Tendency to Colour

Keeping

Colouring

Colour in General Nature

Colour of Particular Objects

Characteristic Colouring

Harmonious Colouring

Genuine Tone

False Tone

Weak Colouring

The Motley

Dread of Theory

Ultimate Aim

Grounds

Pigments

Allegorical, Symbolical, Mystical Application of Colour

Concluding Observations

OUTLINE

OF A

THEORY OF COLOURS.

"Si vera nostra sunt aut falsa, erunt talia, licet nostra

per vitam defendimus. Post fata nostra pueri qui nunc ludunt

nostri judices erunt."

INTRODUCTION.

The desire of knowledge is first stimulated in us when remarkable

phenomena attract our attention. In order that this attention be

continued, it is necessary that we should feel some interest in

exercising it, and thus by degrees we become better acquainted with the

object of our curiosity. During this process of observation we remark

at first only a vast variety which presses indiscriminately on our

view; we are forced to separate, to distinguish, and again to combine;

by which means at last a certain order arises which admits of being

surveyed with more or less satisfaction.

To accomplish this, only in a certain degree, in any department,

requires an unremitting and close application; and we find, for this

reason, that men prefer substituting a general theoretical view, or

some system of explanation, for the facts themselves, instead of taking

the trouble to make themselves first acquainted with cases in detail

and then constructing a whole.

The attempt to describe and class the phenomena of colours has been

only twice made: first by Theophrastus,[1] and in modern times by

Boyle. The pretensions of the present essay to the third place will

hardly be disputed.

Our historical survey enters into further details. Here we merely

observe that in the last century such a classification was not to be

thought of, because Newton had based his hypothesis on a phenomenon

exhibited in a complicated and secondary state; and to this the other

cases that forced themselves on the attention were contrived to be

referred, when they could not be passed over in silence; just as an

astronomer would do, if from whim he were to place the moon in the

centre of our system; he would be compelled to make the earth, sun, and

planets revolve round the lesser body, and be forced to disguise and

gloss over the error of his first assumption by ingenious calculations

and plausible statements.

In our prefatory observations we assumed the reader to be acquainted

with what was known respecting light; here we assume the same with

regard to the eye. We observed that all nature manifests itself by

means of colours to the sense of sight. We now assert, extraordinary as

it may in some degree appear, that the eye sees no form, inasmuch as

light, shade, and colour together constitute that which to our vision

distinguishes object from object, and the parts of an object from each

other. From these three, light, shade, and colour, we construct the

visible world, and thus, at the same time, make painting possible,

an art which has the power of producing on a flat surface a much more

perfect visible world than the actual one can be.

The eye may be said to owe its existence to light, which calls forth,

as it were, a sense that is akin to itself; the eye, in short, is

formed with reference to light, to be fit for the action of light; the

light it contains corresponding with the light without.

We are here reminded of a significant adage in constant use with the

ancient Ionian school--"Like is only known by Like;" and again, of the

words of an old mystic writer, which may be thus rendered, "If the eye

were not sunny, how could we perceive light? If God's own strength

lived not in us, how could we delight in Divine things?" This immediate

affinity between light and the eye will be denied by none; to consider

them as identical in substance is less easy to comprehend. It will be

more intelligible to assert that a dormant light resides in the eye,

and that it may be excited by the slightest cause from within or from

without. In darkness we can, by an effort of imagination, call up the

brightest images; in dreams objects appear to us as in broad daylight;

awake, the slightest external action of light is perceptible, and if

the organ suffers an actual shock, light and colours spring forth.

Here, however, those who are wont to proceed according to a certain

method, may perhaps observe that as yet we have not decidedly explained

what colour is. This question, like the definition of light and the

eye, we would for the present evade, and would appeal to our inquiry

itself, where we have circumstantially shown how colour is produced.

We have only therefore to repeat that colour is a law of nature in

relation with the sense of sight. We must assume, too, that every one

has this sense, that every one knows the operation of nature on it, for

to a blind man it would be impossible to speak of colours.

That we may not, however, appear too anxious to shun such an

explanation, we would restate what has been said as follows: colour is

an elementary phenomenon in nature adapted to the sense of vision; a

phenomenon which, like all others, exhibits itself by separation and

contrast, by commixture and union, by augmentation and neutralization,

by communication and dissolution: under these general terms its nature

may be best comprehended.

We do not press this mode of stating the subject on any one. Those

who, like ourselves, find it convenient, will readily adopt it; but we

have no desire to enter the lists hereafter in its defence. From time

immemorial it has been dangerous to treat of colour; so much so, that

one of our predecessors ventured on a certain occasion to say, "The ox

becomes furious if a red cloth is shown to him; but the philosopher,

who speaks of colour only in a general way, begins to rave."

Nevertheless, if we are to proceed to give some account of our work, to

which we have appealed, we must begin by explaining how we have classed

the different conditions under which colour is produced. We found three

modes in which it appears; three classes of colours, or rather three

exhibitions of them all. The distinctions of these classes are easily

expressed.

Thus, in the first instance, we considered colours, as far as they

may be said to belong to the eye itself, and to depend on an action

and re-action of the organ; next, they attracted our attention as

perceived in, or by means of, colourless mediums; and lastly, where

we could consider them as belonging to particular substances. We have

denominated the first, physiological, the second, physical, the third,

chemical colours. The first are fleeting and not to be arrested; the

next are passing, but still for a while enduring; the last may be made

permanent for any length of time.

Having separated these classes and kept them as distinct as possible,

with a view to a clear, didactic exposition, we have been enabled at

the same time to exhibit them in an unbroken series, to connect the

fleeting with the somewhat more enduring, and these again with the

permanent hues; and thus, after having carefully attended to a distinct

classification in the first instance, to do away with it again when a

larger view was desirable.

In a fourth division of our work we have therefore treated generally

what was previously detailed under various particular conditions, and

have thus, in fact, given a sketch for a future theory of colours. We

will here only anticipate our statements so far as to observe, that

light and darkness, brightness and obscurity, or if a more general

expression is preferred, light and its absence, are necessary to the

production of colour. Next to the light, a colour appears which we call

yellow; another appears next to the darkness, which we name blue. When

these, in their purest state, are so mixed that they are exactly equal,

they produce a third colour called green. Each of the two first-named

colours can however of itself produce a new tint by being condensed or

darkened. They thus acquire a reddish appearance which can be increased

to so great a degree that the original blue or yellow is hardly to

be recognised in it: but the intensest and purest red, especially in

physical cases, is produced when the two extremes of the yellow-red

and blue-red are united. This is the actual state of the appearance

and generation of colours. But we can also assume an existing red in

addition to the definite existing blue and yellow, and we can produce

contrariwise, by mixing, what we directly produced by augmentation or

deepening. With these three or six colours, which may be conveniently

included in a circle, the elementary doctrine of colours is alone

concerned. All other modifications, which may be extended to infinity,

have reference more to the application,--have reference to the

technical operations of the painter and dyer, and the various purposes

of artificial life. To point out another general quality, we may

observe that colours throughout are to be considered as half-lights, as

half-shadows, on which account if they are so mixed as reciprocally to

destroy their specific hues, a shadowy tint, a grey, is produced.

In the fifth division of our inquiry we had proposed to point out

the relations in which we should wish our doctrine of colours to

stand to other pursuits. Important as this part of our work is, it

is perhaps on this very account not so successful as we could wish.

Yet when we reflect that strictly speaking these relations cannot be

described before they exist, we may console ourselves if we have in

some degree failed in endeavouring for the first time to define them.

For undoubtedly we should first wait to see how those whom we have

endeavoured to serve, to whom we have intended to make an agreeable and

useful offering, how such persons, we say, will accept the result of

our utmost exertion: whether they will adopt it, whether they will make

use of it and follow it up, or whether they will repel, reject, and

suffer it to remain unassisted and neglected.

Meanwhile, we venture to express what we believe and hope. From the

philosopher we believe we merit thanks for having traced the phenomena

of colours to their first sources, to the circumstances under which

they simply appear and are, and beyond which no further explanation

respecting them is possible. It will, besides, be gratifying to him

that we have arranged the appearances described in a form that admits

of being easily surveyed, even should he not altogether approve of the

arrangement itself.

The medical practitioner, especially him whose study it is to watch

over the organ of sight, to preserve it, to assist its defects and to

cure its disorders, we reckon to make especially our friend. In the

chapter on the physiological colours, in the Appendix relating to those

that are more strictly pathological, he will find himself quite in his

own province. We are not without hopes of seeing the physiological

phenomena,--a hitherto neglected, and, we may add, most important

branch of the theory of colours,--completely investigated through the

exertions of those individuals who in our own times are treating this

department with success.

The investigator of nature should receive us cordially, since we

enable him to exhibit the doctrine of colours in the series of other

elementary phenomena, and at the same time enable him to make use of a

corresponding nomenclature, nay, almost the same words and designations

as under the other rubrics. It is true we give him rather more trouble

as a teacher, for the chapter of colours is not now to be dismissed

as heretofore with a few paragraphs and experiments; nor will the

scholar submit to be so scantily entertained as he has hitherto been,

without murmuring. On the other hand, an advantage will afterwards

arise out of this: for if the Newtonian doctrine was easily learnt,

insurmountable difficulties presented themselves in its application.

Our theory is perhaps more difficult to comprehend, but once known, all

is accomplished, for it carries its application along with it.

The chemist who looks upon colours as indications by which he may

detect the more secret properties of material things, has hitherto

found much inconvenience in the denomination and description of

colours; nay, some have been induced after closer and nicer examination

to look upon colour as an uncertain and fallacious criterion in

chemical operations. Yet we hope by means of our arrangement and the

nomenclature before alluded to, to bring colour again into credit,

and to awaken the conviction that a progressive, augmenting, mutable

quality, a quality which admits of alteration even to inversion, is not

fallacious, but rather calculated to bring to light the most delicate

operations of nature.

In looking a little further round us, we are not without fears

that we may fail to satisfy another class of scientific men. By an

extraordinary combination of circumstances the theory of colours

has been drawn into the province and before the tribunal of the

mathematician, a tribunal to which it cannot be said to be amenable.

This was owing to its affinity with the other laws of vision which the

mathematician was legitimately called upon to treat. It was owing,

again, to another circumstance: a great mathematician had investigated

the theory of colours, and having been mistaken in his observations as

an experimentalist, he employed the whole force of his talent to give

consistency to this mistake. Were both these circumstances considered,

all misunderstanding would presently be removed, and the mathematician

would willingly co-operate with us, especially in the physical

department of the theory.

To the practical man, to the dyer, on the other hand, our labour must

be altogether acceptable; for it was precisely those who reflected on

the facts resulting from the operations of dyeing who were the least

satisfied with the old theory: they were the first who perceived the

insufficiency of the Newtonian doctrine. The conclusions of men are

very different according to the mode in which they approach a science

or branch of knowledge; from which side, through which door they

enter. The literally practical man, the manufacturer, whose attention

is constantly and forcibly called to the facts which occur under his

eye, who experiences benefit or detriment from the application of his

convictions, to whom loss of time and money is not indifferent, who

is desirous of advancing, who aims at equalling or surpassing what

others have accomplished,--such a person feels the unsoundness and

erroneousness of a theory much sooner than the man of letters, in whose

eyes words consecrated by authority are at last equivalent to solid

coin; than the mathematician, whose formula always remains infallible,

even although the foundation on which it is constructed may not square

with it. Again, to carry on the figure before employed, in entering

this theory from the side of painting, from the side of æsthetic[2]

colouring generally, we shall be found to have accomplished a

most thank-worthy office for the artist. In the sixth part we have

endeavoured to define the effects of colour as addressed at once to

the eye and mind, with a view to making them more available for the

purposes of art. Although much in this portion, and indeed throughout,

has been suffered to remain as a sketch, it should be remembered that

all theory can in strictness only point out leading principles, under

the guidance of which, practice may proceed with vigour and be enabled

to attain legitimate results.

[1] The treatise to which the author alludes in more generally ascribed

to Aristotle.--T.

[2] Æsthetic--belonging to taste as mere internal sense, from

αἰσθάνομαι, to feel; the word was first used by Wolf.--T.

PART I.

PHYSIOLOGICAL COLOURS.

1.

We naturally place these colours first, because they belong altogether,

or in a great degree, to the _subject_[1]--to the eye itself. They

are the foundation of the whole doctrine, and open to our view the

chromatic harmony on which so much difference of opinion has existed.

They have been hitherto looked upon as extrinsic and casual, as

illusion and infirmity: their appearances have been known from ancient

date; but, as they were too evanescent to be arrested, they were

banished into the region of phantoms, and under this idea have been

very variously described.

2.

Thus they are called _colores adventicii_ by Boyle; _imaginarii_ and

_phantastici_ by Rizetti; by Buffon, _couleurs accidentelles_; by

Scherfer, _scheinfarben_ (apparent colours); _ocular illusions_ and

_deceptions of sight_ by many; by Hamberger, _vitia fugitiva_; by

Darwin, _ocular spectra_.

3.

We have called them physiological because they belong to the eye in a

healthy state; because we consider them as the necessary conditions

of vision; the lively alternating action of which, with reference to

external objects and a principle within it, is thus plainly indicated.

4.

To these we subjoin the pathological colours, which, like all

deviations from a constant law, afford a more complete insight into the

nature of the physiological colours.

EFFECTS OF LIGHT AND DARKNESS ON THE EYE.

5.

The retina, after being acted upon by light or darkness, is found to be

in two different states, which are entirely opposed to each other.

6.

If we keep the eyes open in a totally dark place, a certain sense of

privation is experienced. The organ is abandoned to itself; it retires

into itself. That stimulating and grateful contact is wanting by means

of which it is connected with the external world, and becomes part of a

whole.

7.

If we look on a white, strongly illumined surface, the eye is dazzled,

and for a time is incapable of distinguishing objects moderately

lighted.

8.

The whole of the retina is acted on in each of these extreme states,

and thus we can only experience one of these effects at a time. In

the one case (6) we found the organ in the utmost relaxation and

susceptibility; in the other (7) in an overstrained state, and scarcely

susceptible at all.

9.

If we pass suddenly from the one state to the other, even without

supposing these to be the extremes, but only, perhaps, a change from

bright to dusky, the difference is remarkable, and we find that the

effects last for some time.

10.

In passing from bright daylight to a dusky place we distinguish nothing

at first: by degrees the eye recovers its susceptibility; strong eyes

sooner than weak ones; the former in a minute, while the latter may

require seven or eight minutes.

11.

The fact that the eye is not susceptible to faint impressions of

light, if we pass from light to comparative darkness, has led to

curious mistakes in scientific observations. Thus an observer, whose

eyes required some time to recover their tone, was long under the

impression that rotten wood did not emit light at noon-day, even in a

dark room. The fact was, he did not see the faint light, because he was

in the habit of passing from bright sunshine to the dark room, and only

subsequently remained so long there that the eye had time to recover

itself.

The same may have happened to Doctor Wall, who, in the daytime, even in

a dark room, could hardly perceive the electric light of amber.

Our not seeing the stars by day, as well as the improved appearance of

pictures seen through a double tube, is also to be attributed to the

same cause.

12.

If we pass from a totally dark place to one illumined by the sun, we

are dazzled. In coming from a lesser degree of darkness to light that

is not dazzling, we perceive all objects clearer and better: hence eyes

that have been in a state of repose are in all cases better able to

perceive moderately distinct appearances.

Prisoners who have been long confined in darkness acquire so great

a susceptibility of the retina, that even in the dark (probably a

darkness very slightly illumined) they can still distinguish objects.

13.

In the act which we call seeing, the retina is at one and the same time

in different and even opposite states. The greatest brightness, short

of dazzling, acts near the greatest darkness. In this state we at once

perceive all the intermediate gradations of _chiaro-scuro_, and all the

varieties of hues.

14.

We will proceed in due order to consider and examine these elements of

the visible world, as well as the relation in which the organ itself

stands to them, and for this purpose we take the simplest objects.

[1] The German distinction between _subject_ and _object_ is so

generally understood and adopted, that it is hardly necessary to

explain that the subject is the _individual_, in this case the

_beholder_; the object, _all that is without him_.--T.

II.

EFFECTS OF BLACK AND WHITE OBJECTS ON THE EYE.

15.

In the same manner as the retina generally is affected by brightness

and darkness, so it is affected by single bright or dark objects.

If light and dark produce different results on the whole retina, so

black and white objects seen at the same time produce the same states

together which light and dark occasioned in succession.

16.

A dark object appears smaller than a bright one of the same size. Let

a white disk be placed on a black ground, and a black disk on a white

ground, both being exactly similar in size; let them be seen together

at some distance, and we shall pronounce the last to be about a fifth

part smaller than the other. If the black circle be made larger by so

much, they will appear equal.[1]

17.

Thus Tycho de Brahe remarked that the moon in conjunction (the darker

state) appears about a fifth part smaller than when in opposition

(the bright full state). The first crescent appears to belong to a

larger disk than the remaining dark portion, which can sometimes be

distinguished at the period of the new moon. Black dresses make people

appear smaller than light ones. Lights seen behind an edge make an

apparent notch in it. A ruler, behind which the flame of a light just

appears, seems to us indented. The rising or setting sun appears to

make a notch in the horizon.

[Illustration]

18.

Black, as the equivalent of darkness, leaves the organ in a state of

repose; white, as the representative of light, excites it. We may,

perhaps, conclude from the above experiment (16) that the unexcited

retina, if left to itself, is drawn together, and occupies a less space

than in its active state, produced by the excitement of light.

Hence Kepler says very beautifully: "Certum est vel in retinâ caussâ

picturæ, vel in spiritibus caussâ impressionis, exsistere dilatationem

lucidorum."--_Paralip. in Vitellionem_, p. 220. Scherfer expresses a

similar conjecture.--Note A.

19.

However this may be, both impressions derived from such objects remain

in the organ itself, and last for some time, even when the external

cause is removed. In ordinary experience we scarcely notice this, for

objects are seldom presented to us which are very strongly relieved

from each other, and we avoid looking at those appearances that dazzle

the sight. In glancing from one object to another, the succession of

images appears to us distinct; we are not aware that some portion of

the impression derived from the object first contemplated passes to

that which is next looked at.

20.

If in the morning, on waking, when the eye is very susceptible, we look

intently at the bars of a window relieved against the dawning sky, and

then shut our eyes or look towards a totally dark place, we shall see a

dark cross on a light ground before us for some time.

21.

Every image occupies a certain space on the retina, and of course a

greater or less space in proportion as the object is seen near or at a

distance. If we shut the eyes immediately after looking at the sun we

shall be surprised to find how small the image it leaves appears.

22.

If, on the other hand, we turn the open eye towards the side of a

room, and consider the visionary image in relation to other objects,

we shall always see it larger in proportion to the distance of the

surface on which it is thrown. This is easily explained by the laws of

perspective, according to which a small object near covers a great one

at a distance.

23.

The duration of these visionary impressions varies with the powers

or structure of the eye in different individuals, just as the time

necessary for the recovery of the tone of the retina varies in passing

from brightness to darkness (10): it can be measured by minutes and

seconds, indeed much more exactly than it could formerly have been

by causing a lighted linstock to revolve rapidly, so as to appear a

circle.--Note B.

24.

But the force with which an impinging light impresses the eye is

especially worthy of attention. The image of the sun lasts longest;

other objects, of various degrees of brightness, leave the traces of

their appearance on the eye for a proportionate time.

25.

These images disappear by degrees, and diminish at once in distinctness

and in size.

26.

They are reduced from the contour inwards, and the impression on some

persons has been that in square images the angles become gradually

blunted till at last a diminished round image floats before the eye.

27.

Such an image, when its impression is no more observable, can,

immediately after, be again revived on the retina by opening and

shutting the eye, thus alternately exciting and resting it.

28.

Images may remain on the retina in morbid affections of the eye for

fourteen, seventeen minutes, or even longer. This indicates extreme

weakness of the organ, its inability to recover itself; while visions

of persons or things which are the objects of love or aversion indicate

the connexion between sense and thought.

29.

If, while the image of the window-bars before mentioned lasts, we

look upon a light grey surface, the cross will then appear light

and the panes dark. In the first case (20) the image was like the

original picture, so that the visionary impression also could continue

unchanged; but in the present instance our attention is excited by a

contrary effect being produced. Various examples have been given by

observers of nature.

30.

The scientific men who made observations in the Cordilleras saw a

bright appearance round the shadows of their heads on some clouds. This

example is a case in point; for, while they fixed their eyes on the

dark shadow, and at the same time moved from the spot, the compensatory

light image appeared to float round the real dark one. If we look at

a black disk on a light grey surface, we shall presently, by changing

the direction of the eyes in the slightest degree, see a bright halo

floating round the dark circle.

A similar circumstance happened to myself: for while, as I sat in the

open air, I was talking to a man who stood at a little distance from me

relieved on a grey sky, it appeared to me, as I slightly altered the

direction of my eyes, after having for some time looked fixedly at him,

that his head was encircled with a dazzling light.

In the same way probably might be explained the circumstance that

persons crossing dewy meadows at sunrise see a brightness round each

other's heads[2]; the brightness in this case may be also iridescent,

as the phenomena of refraction come into the account.

Thus again it has been asserted that the shadows of a balloon thrown on

clouds were bordered with bright and somewhat variegated circles.

Beccaria made use of a paper kite in some experiments on electricity.

Round this kite appeared a small shining cloud varying in size; the

same brightness was even observed round part of the string. Sometimes

it disappeared, and if the kite moved faster the light appeared to

float to and fro for a few moments on the place before occupied. This

appearance, which could not be explained by those who observed it at

the time, was the image which the eye retained of the kite relieved as

a dark mass on a bright sky; that image being changed into a light mass

on a comparatively dark background.

In optical and especially in chromatic experiments, where the observer

has to do with bright lights whether colourless or coloured, great care

should be taken that the spectrum which the eye retains in consequence

of a previous observation does not mix with the succeeding one, and

thus affect the distinctness and purity of the impression.

31.

These appearances have been explained as follows: That portion of the

retina on which the dark cross (29) was impressed is to be considered

in a state of repose and susceptibility. On this portion therefore the

moderately light surface acted in a more lively manner than on the rest

of the retina, which had just been impressed with the light through

the panes, and which, having thus been excited by a much stronger

brightness, could only view the grey surface as a dark.

32.

This mode of explanation appears sufficient for the cases in question,

but, in the consideration of phenomena hereafter to be adduced, we are

forced to trace the effects to higher sources.

33.

The eye after sleep exhibits its vital elasticity more especially by

its tendency to alternate its impressions, which in the simplest form

change from dark to light, and from light to dark. The eye cannot for a

moment remain in a particular state determined by the object it looks

upon. On the contrary, it is forced to a sort of opposition, which, in

contrasting extreme with extreme, intermediate degree with intermediate

degree, at the same time combines these opposite impressions, and thus

ever tends to a whole, whether the impressions are successive, or

simultaneous and confined to one image.

34.

Perhaps the peculiarly grateful sensation which we experience in

looking at the skilfully treated chiaro-scuro of colourless pictures

and similar works of art arises chiefly from the _simultaneous_

impression of a whole, which by the organ itself is sought, rather than

arrived at, in _succession_, and which, whatever may be the result, can

never be arrested.

[1] Plate 1. fig. 1.

[2] See the Life of Benvenuto Cellini, vol. i. p. 453. Milan edition,

1806.--T.

III.

GREY SURFACES AND OBJECTS.

35.

A moderate light is essential to many chromatic experiments. This can

be presently obtained by surfaces more or less grey, and thus we have

at once to make ourselves acquainted with this simplest kind of middle

tint, with regard to which it is hardly necessary to observe, that

in many cases a white surface in shadow, or in a low light, may be

considered equivalent to a grey.

36.

Since a grey surface is intermediate between brightness and darkness,

it admits of our illustrating a phenomenon before described (29) by an

easy experiment.

37.

Let a black object be held before a grey surface, and let the

spectator, after looking steadfastly at it, keep his eyes unmoved while

it is taken away: the space it occupied appears much lighter. Let a

white object be held up in the same manner: on taking it away the space

it occupied will appear much darker than the rest of the surface. Let

the spectator in both cases turn his eyes this way and that on the

surface, the visionary images will move in like manner.

38.

A grey object on a black ground appears much brighter than the same

object on a white ground. If both comparisons are seen together the

spectator can hardly persuade himself that the two greys are identical.

We believe this again to be a proof of the great excitability of the

retina, and of the silent resistance which every vital principle is

forced to exhibit when any definite or immutable state is presented to

it. Thus inspiration already presupposes expiration; thus every systole

its diastole. It is the universal formula of life which manifests

itself in this as in all other cases. When darkness is presented to

the eye it demands brightness, and _vice versâ_: it shows its vital

energy, its fitness to receive the impression of the object, precisely

by spontaneously tending to an opposite state.

IV.

DAZZLING COLOURLESS OBJECTS.

39.

If we look at a dazzling, altogether colourless object, it makes a

strong lasting impression, and its after-vision is accompanied by an

appearance of colour.

40.

Let a room be made as dark as possible; let there be a circular opening

in the window-shutter about three inches in diameter, which may be

closed or not at pleasure. The sun being suffered to shine through this

on a white surface, let the spectator from some little distance fix his

eyes on the bright circle thus admitted. The hole being then closed,

let him look towards the darkest part of the room; a circular image

will now be seen to float before him. The middle of this circle will

appear bright, colourless, or somewhat yellow, but the border will at

the same moment appear red.

After a time this red, increasing towards the centre, covers the whole

circle, and at last the bright central point. No sooner, however, is

the whole circle red than the edge begins to be blue, and the blue

gradually encroaches inwards on the red. When the whole is blue

the edge becomes dark and colourless. This darker edge again slowly

encroaches on the blue till the whole circle appears colourless. The

image then becomes gradually fainter, and at the same time diminishes

in size. Here again we see how the retina recovers itself by a

succession of vibrations after the powerful external impression it

received. (25, 26.)

41.

By several repetitions similar in result, I found the comparative

duration of these appearances in my own case to be as follows:--

I looked on the bright circle five seconds, and then, having closed

the aperture, saw the coloured visionary circle floating before me.

After thirteen seconds it was altogether red; twenty-nine seconds

next elapsed till the whole was blue, and forty-eight seconds till

it appeared colourless. By shutting and opening the eye I constantly

revived the image, so that it did not quite disappear till seven

minutes had elapsed.

Future observers may find these periods shorter or longer as their

eyes may be stronger or weaker (23), but it would be very remarkable

if, notwithstanding such variations, a corresponding proportion as to

relative duration should be found to exist.

42.

But this remarkable phenomenon no sooner excites our attention than we

observe a new modification of it.

If we receive the impression of the bright circle as before, and then

look on a light grey surface in a moderately lighted room, an image

again floats before us; but in this instance a dark one: by degrees it

is encircled by a green border that gradually spreads inwards over the

whole circle, as the red did in the former instance. As soon as this

has taken place a dingy yellow appears, and, filling the space as the

blue did before, is finally lost in a negative shade.

43.

These two experiments may be combined by placing a black and a white

plane surface next each other in a moderately lighted room, and then

looking alternately on one and the other as long as the impression of

the light circle lasts: the spectator will then perceive at first a red

and green image alternately, and afterwards the other changes. After a

little practice the two opposite colours may be perceived at once, by

causing the floating image to fall on the junction of the two planes.

This can be more conveniently done if the planes are at some distance,

for the spectrum then appears larger.

44.

I happened to be in a forge towards evening at the moment when a

glowing mass of iron was placed on the anvil; I had fixed my eyes

steadfastly on it, and, turning round, I looked accidentally into an

open coal-shed: a large red image now floated before my eyes, and, as I

turned them from the dark opening to the light boards of which the shed

was constructed, the image appeared half green, half red, according as

it had a lighter or darker ground behind it. I did not at that time

take notice of the subsequent changes of this appearance.

45.

The after-vision occasioned by a total dazzling of the retina

corresponds with that of a circumscribed bright object. The red colour

seen by persons who are dazzled with snow belongs to this class of

phenomena, as well as the singularly beautiful green colour which dark

objects seem to wear after looking long on white paper in the sun. The

details of such experiments may be investigated hereafter by those

whose young eyes are capable of enduring such trials further for the

sake of science.

46.

With these examples we may also class the black letters which in the

evening light appear red. Perhaps we might insert under the same

category the story that drops of blood appeared on the table at which

Henry IV. of France had seated himself with the Duc de Guise to play at

dice.

V.

COLOURED OBJECTS.

47.

We have hitherto seen the physiological colours displayed in the

after-vision of colourless bright objects, and also in the after-vision

of general colourless brightness; we shall now find analogous

appearances if a given colour be presented to the eye: in considering

this, all that has been hitherto detailed must be present to our

recollection.

48.

The impression of coloured objects remains in the eye like that of

colourless ones, but in this case the energy of the retina, stimulated

as it is to produce the opposite colour, will be more apparent.

49.

Let a small piece of bright-coloured paper or silk stuff be held before

a moderately lighted white surface; let the observer look steadfastly

on the small coloured object, and let it be taken away after a time

while his eyes remain unmoved; the spectrum of another colour will then

be visible on the white plane. The coloured paper may be also left in

its place while the eye is directed to another part of the white plane;

the same spectrum will be visible there too, for it arises from an

image which now belongs to the eye.

50.

In order at once to see what colour will be evoked by this contrast,

the chromatic circle[1] may be referred to. The colours are here

arranged in a general way according to the natural order, and the

arrangement will be found to be directly applicable in the present

case; for the colours diametrically opposed to each other in this

diagram are those which reciprocally evoke each other in the eye. Thus,

yellow demands purple; orange, blue; red, green; and _vice versâ_: thus

again all intermediate gradations reciprocally evoke each other; the

simpler colour demanding the compound, and _vice versâ_.--Note C.

51.

The cases here under consideration occur oftener than we are aware in

ordinary life; indeed, an attentive observer sees these appearances

everywhere, while, on the other hand, the uninstructed, like our

predecessors, consider them as temporary visual defects, sometimes

even as symptoms of disorders in the eye, thus exciting serious

apprehensions. A few remarkable instances may here be inserted.

52.

I had entered an inn towards evening, and, as a well-favoured girl,

with a brilliantly fair complexion, black hair, and a scarlet bodice,

came into the room, I looked attentively at her as she stood before me

at some distance in half shadow. As she presently afterwards turned

away, I saw on the white wall, which was now before me, a black face

surrounded with a bright light, while the dress of the perfectly

distinct figure appeared of a beautiful sea-green.

53.

Among the materials for optical experiments, there are portraits with

colours and shadows exactly opposite to the appearance of nature. The

spectator, after having looked at one of these for a time, will see the

visionary figure tolerably true to nature. This is conformable to the

same principles, and consistent with experience, for, in the former

instance, a negress with a white head-dress would have given me a

white face surrounded with black. In the case of the painted figures,

however, which are commonly small, the parts are not distinguishable by

every one in the after-image.

54.

A phenomenon which has before excited attention among the observers of

nature is to be attributed, I am persuaded, to the same cause.

It has been stated that certain flowers, towards evening in summer,

coruscate, become phosphorescent, or emit a momentary light. Some

persons have described their observation of this minutely. I had often

endeavoured to witness it myself, and had even resorted to artificial

contrivances to produce it.

On the 19th of June, 1799, late in the evening, when the twilight was

deepening into a clear night, as I was walking up and down the garden

with a friend, we very distinctly observed a flame-like appearance

near the oriental poppy, the flowers of which are remarkable for their

powerful red colour. We approached the place and looked attentively

at the flowers, but could perceive nothing further, till at last, by

passing and repassing repeatedly, while we looked sideways on them, we

succeeded in renewing the appearance as often as we pleased. It proved

to be a physiological phenomenon, such as others we have described, and

the apparent coruscation was nothing but the spectrum of the flower in

the compensatory blue-green colour.

In looking directly at a flower the image is not produced, but it

appears immediately as the direction of the eye is altered. Again, by

looking sideways on the object, a double image is seen for a moment,

for the spectrum then appears near and on the real object.

The twilight accounts for the eye being in a perfect state of repose,

and thus very susceptible, and the colour of the poppy is sufficiently

powerful in the summer twilight of the longest days to act with

full effect and produce a compensatory image. I have no doubt these

appearances might be reduced to experiment, and the same effect

produced by pieces of coloured paper. Those who wish to take the most

effectual means for observing the appearance in nature--suppose in a

garden--should fix the eyes on the bright flowers selected for the

purpose, and, immediately after, look on the gravel path. This will

be seen studded with spots of the opposite colour. The experiment is

practicable on a cloudy day, and even in the brightest sunshine, for

the sun-light, by enhancing the brilliancy of the flower, renders it

fit to produce the compensatory colour sufficiently distinct to be

perceptible even in a bright light. Thus, peonies produce beautiful

green, marigolds vivid blue spectra.

55.

As the opposite colour is produced by a constant law in experiments

with coloured objects on portions of the retina, so the same effect

takes place when the whole retina is impressed with a single colour. We

may convince ourselves of this by means of coloured glasses. If we look

long through a blue pane of glass, everything will afterwards appear

in sunshine to the naked eye, even if the sky is grey and the scene

colourless. In like manner, in taking off green spectacles, we see all

objects in a red light. Every decided colour does a certain violence to

the eye, and forces the organ to opposition.

56.

We have hitherto seen the opposite colours producing each other

successively on the retina: it now remains to show by experiment

that the same effects can exist simultaneously. If a coloured object

impinges on one part of the retina, the remaining portion at the same

moment has a tendency to produce the compensatory colour. To pursue

a former experiment, if we look on a yellow piece of paper placed

on a white surface, the remaining part of the organ has already a

tendency to produce a purple hue on the colourless surface: in this

case the small portion of yellow is not powerful enough to produce

this appearance distinctly, but, if a white paper is placed on a yellow

wall, we shall see the white tinged with a purple hue.

57.

Although this experiment may be made with any colours, yet red and

green are particularly recommended for it, because these colours seem

powerfully to evoke each other. Numerous instances occur in daily

experience. If a green paper is seen through striped or flowered

muslin, the stripes or flowers will appear reddish. A grey building

seen through green pallisades appears in like manner reddish. A

modification of this tint in the agitated sea is also a compensatory

colour: the light side of the waves appears green in its own colour,

and the shadowed side is tinged with the opposite hue. The different

direction of the waves with reference to the eye produces the same

effect. Objects seen through an opening in a red or green curtain

appear to wear the opposite hue. These appearances will present

themselves to the attentive observer on all occasions, even to an

unpleasant degree.

58.

Having made ourselves acquainted with the simultaneous exhibition of

these effects in direct cases, we shall find that we can also observe

them by indirect means. If we place a piece of paper of a bright

orange colour on the white surface, we shall, after looking intently

at it, scarcely perceive the compensatory colour on the rest of the

surface: but when we take the orange paper away, and when the blue

spectrum appears in its place, immediately as this spectrum becomes

fully apparent, the rest of the surface will be overspread, as if by a

flash, with a reddish-yellow light, thus exhibiting to the spectator

in a lively manner the productive energy of the organ, in constant

conformity with the same law.

59.

As the compensatory colours easily appear, where they do not exist in

nature, near and after the original opposite ones, so they are rendered

more intense where they happen to mix with a similar real hue. In a

court which was paved with grey limestone flags, between which grass

had grown, the grass appeared of an extremely beautiful green when

the evening clouds threw a scarcely perceptible reddish light on the

pavement. In an opposite case we find, in walking through meadows,

where we see scarcely anything but green, the stems of trees and the

roads often gleam with a reddish hue. This tone is not uncommon in

the works of landscape painters, especially those who practice in

water-colours: they probably see it in nature, and thus, unconsciously

imitating it, their colouring is criticised as unnatural.

60.

These phenomena are of the greatest importance, since they direct our

attention to the laws of vision, and are a necessary preparation for

future observations on colours. They show that the eye especially

demands completeness, and seeks to eke out the colorific circle in

itself. The purple or violet colour suggested by yellow contains red

and blue; orange, which responds to blue, is composed of yellow and

red; green, uniting blue and yellow, demands red; and so through all

gradations of the most complicated combinations. That we are compelled

in this case to assume three leading colours has been already remarked

by other observers.

61.

When in this completeness the elements of which it is composed are

still appreciable by the eye, the result is justly called harmony. We

shall subsequently endeavour to show how the theory of the harmony of

colours may be deduced from these phenomena, and how, simply through

these qualities, colours may be capable of being applied to æsthetic

purposes. This will be shown when we have gone through the whole circle

of our observations, returning to the point from which we started.

[1] Plate 1, fig. 3.

VI.

COLOURED SHADOWS.

62.

Before, however, we proceed further, we have yet to observe some very

remarkable cases of the vivacity with which the suggested colours

appear in the neighbourhood of others: we allude to coloured shadows.

To arrive at these we first turn our attention to shadows that are

colourless or negative.

63.

A shadow cast by the sun, in its full brightness, on a white surface,

gives us no impression of colour; it appears black, or, if a contrary

light (here assumed to differ only in degree) can act upon it, it is

only weaker, half-lighted, grey.

64.

Two conditions are necessary for the existence of coloured shadows:

first, that the principal light tinge the white surface with some hue;

secondly, that a contrary light illumine to a certain extent the cast

shadow.

65.

Let a short, lighted candle be placed at twilight on a sheet of white

paper. Between it and the declining daylight let a pencil be placed

upright, so that its shadow thrown by the candle may be lighted, but

not overcome, by the weak daylight: the shadow will appear of the most

beautiful blue.

66.

That this shadow is blue is immediately evident; but we can only

persuade ourselves by some attention that the white paper acts as a

reddish yellow, by means of which the complemental blue is excited in

the eye.--Note D.

67.

In all coloured shadows, therefore, we must presuppose a colour excited

or suggested by the hue of the surface on which the shadow is thrown.

This may be easily found to be the case by attentive consideration, but

we may convince ourselves at once by the following experiment.

68.

Place two candles at night opposite each other on a white surface; hold

a thin rod between them upright, so that two shadows be cast by it;

take a coloured glass and hold it before one of the lights, so that

the white paper appear coloured; at the same moment the shadow cast by

the coloured light and slightly illumined by the colourless one will

exhibit the complemental hue.

69.

An important consideration suggests itself here, to which we shall

frequently have occasion to return. Colour itself is a degree of

darkness _σκιερόν_; hence Kircher is perfectly right in calling it

_lumen opacatum_. As it is allied to shadow, so it combines readily

with it; it appears to us readily in and by means of shadow the

moment a suggesting cause presents itself. We could not refrain from

adverting at once to a fact which we propose to trace and develop

hereafter.--Note E.

70.

Select the moment in twilight when the light of the sky is still

powerful enough to cast a shadow which cannot be entirely effaced by

the light of a candle. The candle may be so placed that a double shadow

shall be visible, one from the candle towards the daylight, and another

from the daylight towards the candle. If the former is blue the latter

will appear orange-yellow: this orange-yellow is in fact, however, only

the yellow-red light of the candle diffused over the whole paper, and

which _becomes visible in shadow_.

71.

This is best exemplified by the former experiment with two candles and

coloured glasses.

The surprising readiness with which shadow assumes a colour will again

invite our attention in the further consideration of reflections and

elsewhere.

72.

Thus the phenomena of coloured shadows may be traced to their cause

without difficulty. Henceforth let any one who sees an instance of

the kind observe only with what hue the light surface on which they

are thrown is tinged. Nay, the colour of the shadow may be considered

as a chromatoscope of the illumined surface, for the spectator may

always assume the colour of the light to be the opposite of that of the

shadow, and by an attentive examination may ascertain this to be the

fact in every instance.

73.

These appearances have been a source of great perplexity to former

observers: for, as they were remarked chiefly in the open air, where

they commonly appeared blue, they were attributed to a certain inherent

blue or blue colouring quality in the air. The inquirer can, however,

convince himself, by the experiment with the candle in a room, that no

kind of blue light or reflection is necessary to produce the effect

in question. The experiment may be made on a cloudy day with white

curtains drawn before the light, and in a room where no trace of blue

exists, and the blue shadow will be only so much the more beautiful.

74.

De Saussure, in the description of his ascent of Mont Blanc, says, "A

second remark, which may not be uninteresting, relates to the colour of

the shadows. These, notwithstanding the most attentive observation, we

never found dark blue, although this had been frequently the case in

the plain. On the contrary, in fifty-nine instances we saw them once

yellowish, six times pale bluish, eighteen times colourless or black,

and thirty-four times pale violet. Some natural philosophers suppose

that these colours arise from accidental vapours diffused in the air,

which communicate their own hues to the shadows; not that the colours

of the shadows are occasioned by the reflection of any given sky colour

or interposition of any given air colour: the above observations seem

to favour this opinion." The instances given by De Saussure may be now

explained and classed with analogous examples without difficulty.

At a great elevation the sky was generally free from vapours, the sun

shone in full force on the snow, so that it appeared perfectly white

to the eye: in this case they saw the shadows quite colourless. If the

air was charged with a certain degree of vapour, in consequence of

which the light snow would assume a yellowish tone, the shadows were

violet-coloured, and this effect, it appears, occurred oftenest. They

saw also bluish shadows, but this happened less frequently; and that

the blue and violet were pale was owing to the surrounding brightness,

by which the strength of the shadows was mitigated. Once only they

saw the shadow yellowish: in this case, as we have already seen (70),

the shadow is cast by a colourless light, and slightly illumined by a

coloured one.

75.

In travelling over the Harz in winter, I happened to descend from the

Brocken towards evening; the wide slopes extending above and below me,

the heath, every insulated tree and projecting rock, and all masses of

both, were covered with snow or hoar-frost. The sun was sinking towards

the Oder ponds[1]. During the day, owing to the yellowish hue of the

snow, shadows tending to violet had already been observable; these

might now be pronounced to be decidedly blue, as the illumined parts

exhibited a yellow deepening to orange.

But as the sun at last was about to set, and its rays, greatly

mitigated by the thicker vapours, began to diffuse a most beautiful

red colour over the whole scene around me, the shadow colour changed

to a green, in lightness to be compared to a sea-green, in beauty to

the green of the emerald. The appearance became more and more vivid:

one might have imagined oneself in a fairy world, for every object had

clothed itself in the two vivid and so beautifully harmonising colours,

till at last, as the sun went down, the magnificent spectacle was lost

in a grey twilight, and by degrees in a clear moon-and-starlight night.

76.

One of the most beautiful instances of coloured shadows may be

observed during the full moon. The candle-light and moon-light may be

contrived to be exactly equal in force; both shadows may be exhibited

with equal strength and clearness, so that both colours balance each

other perfectly. A white surface being placed opposite the full moon,

and the candle being placed a little on one side at a due distance,

an opaque body is held before the white plane, A double shadow will

then be seen: that cast by the moon and illumined by the candle-light

will be a powerful red-yellow; and contrariwise, that cast by the

candle and illumined by the moon will appear of the most beautiful

blue. The shadow, composed of the union of the two shadows, where

they cross each other, is black. The yellow shadow (74) cannot perhaps

be exhibited in a more striking manner. The immediate vicinity of

the blue and the interposing black shadow make the appearance the

more agreeable. It will even be found, if the eye dwells long on

these colours, that they mutually evoke and enhance each other, the

increasing red in the one still producing its contrast, viz. a kind of

sea-green.

77.

We are here led to remark that in this, and in all cases, a moment or

two may perhaps be necessary to produce the complemental colour. The

retina must be first thoroughly impressed with the demanding hue before

the responding one can be distinctly observable.

78.

When divers are under water, and the sunlight shines into the

diving-bell, everything is seen in a red light (the cause of which

will be explained hereafter), while the shadows appear green. The very

same phenomenon which I observed on a high mountain (75) is presented

to others in the depths of the sea, and thus Nature throughout is in

harmony with herself.

79.

Some observations and experiments which equally illustrate what has

been stated with regard to coloured objects and coloured shadows may

be here added. Let a white paper blind be fastened inside the window

on a winter evening; in this blind let there be an opening, through

which the snow of some neighbouring roof can be seen. Towards dusk let

a candle be brought into the room; the snow seen through the opening

will then appear perfectly blue, because the paper is tinged with warm

yellow by the candle-light. The snow seen through the aperture is here

equivalent to a shadow illumined by a contrary light (76), and may also

represent a grey disk on a coloured surface (56).

80.

Another very interesting experiment may conclude these examples. If we

take a piece of green glass of some thickness, and hold it so that the

window bars be reflected in it, they will appear double owing to the

thickness of the glass. The image which is reflected from the under

surface of the glass will be green; the image which is reflected from

the upper surface, and which should be colourless, will appear red.

The experiment may be very satisfactorily made by pouring water into

a vessel, the inner surface of which can act as a mirror; for both

reflections may first be seen colourless while the water is pure, and

then by tinging it, they will exhibit two opposite hues.

[1] Reservoirs in which water is collected from various small streams,

to work the mines.--T.

VII.

FAINT LIGHTS.

81.

Light, in its full force, appears purely white, and it gives this

impression also in its highest degree of dazzling splendour. Light,

which is not so powerful, can also, under various conditions, remain

colourless. Several naturalists and mathematicians have endeavoured to

measure its degrees--Lambert, Bouguer, Rumford.

82.

Yet an appearance of colour presently manifests itself in fainter

lights, for in their relation to absolute light they resemble the

coloured spectra of dazzling objects (39).

83.

A light of any kind becomes weaker, either when its own force, from

whatever cause, is diminished, or when the eye is so circumstanced or

placed, that it cannot be sufficiently impressed by the action of the

light. Those appearances which may be called objective, come under the

head of physical colours. We will only advert here to the transition

from white to red heat in glowing iron. We may also observe that the

flames of lights at night appear redder in proportion to their distance

from the eye.--Note F.

84.

Candle-light at night acts as yellow when seen near; we can perceive

this by the effect it produces on other colours. At night a pale yellow

is hardly to be distinguished from white; blue approaches to green, and

rose-colour to orange.

85.

Candle-light at twilight acts powerfully as a yellow light: this

is best proved by the purple blue shadows which, under these

circumstances, are evoked by the eye.

86.

The retina may be so excited by a strong light that it cannot perceive

fainter lights (11): if it perceive these they appear coloured: hence

candle-light by day appears reddish, thus resembling, in its relation

to fuller light, the spectrum of a dazzling object; nay, if at night we

look long and intently on the flame of a light, it appears to increase

in redness.

87.

There are faint lights which, notwithstanding their moderate lustre,

give an impression of a white, or, at the most, of a light yellow

appearance on the retina; such as the moon in its full splendour.

Rotten wood has even a kind of bluish light. All this will hereafter be

the subject of further remarks.

88.

If at night we place a light near a white or greyish wall so that the

surface be illumined from this central point to some extent, we find,

on observing the spreading light at some distance, that the boundary of

the illumined surface appears to be surrounded with a yellow circle,

which on the outside tends to red-yellow. We thus observe that when

light direct or reflected does not act in its full force, it gives an

impression of yellow, of reddish, and lastly even of red. Here we find

the transition to halos which we are accustomed to see in some mode or

other round luminous points.

VIII.

SUBJECTIVE HALOS.

89.

Halos may be divided into subjective and objective. The latter will

be considered under the physical colours; the first only belong here.

These are distinguished from the objective halos by the circumstance

of their vanishing when the point of light which produces them on the

retina is covered.

90.

We have before noticed the impression of a luminous object on the

retina, and seen that it appears larger: but the effect is not at

an end here, it is not confined to the impression of the image; an

expansive action also takes place, spreading from the centre.

91.

That a nimbus of this kind is produced round the luminous image in the

eye may be best seen in a dark room, if we look towards a moderately

large opening in the window-shutter. In this case the bright image is

surrounded by a circular misty light. I saw such a halo bounded by a

yellow and yellow-red circle on opening my eyes at dawn, on an occasion

when I passed several nights in a bed-carriage.

92.

Halos appear most vivid when the eye is susceptible from having been in

a state of repose. A dark background also heightens their appearance.

Both causes account for our seeing them so strong if a light is

presented to the eyes on waking at night. These conditions were

combined when Descartes after sleeping, as he sat in a ship, remarked

such a vividly-coloured halo round the light.

93.

A light must shine moderately, not dazzle, in order to produce the

impression of a halo in the eye; at all events the halos of dazzling

lights cannot be observed. We see a splendour of this kind round the

image of the sun reflected from the surface of water.

94.

A halo of this description, attentively observed, is found to be

encircled towards its edge with a yellow border: but even here the

expansive action, before alluded to, is not at an end, but appears

still to extend in varied circles.

95.

Several cases seem to indicate a circular action of the retina, whether

owing to the round form of the eye itself and its different parts, or

to some other cause.

96.

If the eye is pressed only in a slight degree from the inner corner,

darker or lighter circles appear. At night, even without pressure, we

can sometimes perceive a succession of such circles emerging from, or

spreading over, each other.

97.

We have already seen that a yellow border is apparent round the white

space illumined by a light placed near it. This may be a kind of

objective halo. (88.)

98.

Subjective halos may be considered as the result of a conflict between

the light and a living surface. From the conflict between the exciting

principle and the excited, an undulating motion arises, which may be

illustrated by a comparison with the circles on water. The stone thrown

in drives the water in all directions; the effect attains a maximum,

it reacts, and being opposed, continues under the surface. The effect

goes on, culminates again, and thus the circles are repeated. If we

have ever remarked the concentric rings which appear in a glass of

water on trying to produce a tone by rubbing the edge; if we call to

mind the intermitting pulsations in the reverberations of bells, we

shall approach a conception of what may take place on the retina when

the image of a luminous object impinges on it, not to mention that as

a living and elastic structure, it has already a circular principle in

its organisation.--Note G.

99.

The bright circular space which appears round the shining object

is yellow, ending in red: then follows a greenish circle, which is

terminated by a red border. This appears to be the usual phenomenon

where the luminous body is somewhat considerable in size. These halos

become greater the more distant we are from the luminous object.

100.

Halos may, however, appear extremely small and numerous when the

impinging image is minute, yet powerful, in its effect. The experiment

is best made with a piece of gold-leaf placed on the ground and

illumined by the sun. In these cases the halos appear in variegated

rays. The iridescent appearance produced in the eye when the sun

pierces through the leaves of trees seems also to belong to the same

class of phenomena.

PATHOLOGICAL COLOURS.

APPENDIX.

101.

We are now sufficiently acquainted with the physiological colours to

distinguish them from the pathological. We know what appearances belong

to the eye in a healthy state, and are necessary to enable the organ to

exert its complete vitality and activity.

102.

Morbid phenomena indicate in like manner the existence of organic

and physical laws: for if a living being deviates from those rules

with reference to which it is constructed, it still seeks to agree

with the general vitality of nature in conformity with general laws,

and throughout its whole course still proves the constancy of those

principles on which the universe has existed, and by which it is held

together.

103.

We will here first advert to a very remarkable state in which the

vision of many persons is found to be. As it presents a deviation

from the ordinary mode of seeing colours, it might be fairly classed

under morbid impressions; but as it is consistent in itself, as it

often occurs, may extend to several members of a family, and probably

does not admit of cure, we may consider it as bordering only on the

nosological cases, and therefore place it first.

104.

I was acquainted with two individuals not more than twenty years of

age, who were thus affected: both had bluish-grey eyes, an acute sight

for near and distant objects, by day-light and candle-light, and their

mode of seeing colours was in the main quite similar.

105.

They agreed with the rest of the world in denominating white, black,

and grey in the usual manner. Both saw white untinged with any hue. One

saw a somewhat brownish appearance in black, and in grey a somewhat

reddish tinge. In general they appeared to have a very delicate

perception of the gradations of light and dark.

106.

They appeared to see yellow, red-yellow, and yellow-red,[1] like

others: in the last case they said they saw the yellow passing as it

were over the red as if glazed: some thickly-ground carmine, which had

dried in a saucer, they called red.

107.

But now a striking difference presented itself. If the carmine was

passed thinly over the white saucer, they would compare the light

colour thus produced to the colour of the sky, and call it blue. If

a rose was shown them beside it, they would, in like manner, call it

blue; and in all the trials which were made, it appeared that they

could not distinguish light blue from rose-colour. They confounded

rose-colour, blue, and violet on all occasions: these colours only

appeared to them to be distinguished from each other by delicate shades

of lighter, darker, intenser, or fainter appearance.

108.

Again they could not distinguish green from dark orange, nor, more

especially, from a red brown.

109.

If any one, accidentally conversing with these individuals, happened

to question them about surrounding objects, their answers occasioned

the greatest perplexity, and the interrogator began to fancy his own

wits were out of order. With some method we may, however, approach to a

nearer knowledge of the law of this deviation from the general law.

110.

These persons, as may be gathered from what has been stated, saw fewer

colours than other people: hence arose the confusion of different

colours. They called the sky rose-colour, and the rose blue, or

_vice versâ_. The question now is: did they see both blue or both

rose-colour? did they see green orange, or orange green?

111.

This singular enigma appears to solve itself, if we assume that they

saw no blue, but, instead of it, a light pure red, a rose-colour.

We can comprehend what would be the result of this by means of the

chromatic diagram.

112.

If we take away blue from the chromatic circle we shall miss violet and

green as well. Pure red occupies the place of blue and violet, and in

again mixing with yellow the red produces orange where green should be.

113.

Professing to be satisfied with this mode of explanation, we have named

this remarkable deviation from ordinary vision "Acyanoblepsia."[2]

We have prepared some coloured figures for its further elucidation,

and in explaining these we shall add some further details. Among the

examples will be found a landscape, coloured in the mode in which the

individuals alluded to appeared to see nature: the sky rose-colour, and

all that should be green varying from yellow to brown red, nearly as

foliage appears to us in autumn[3].--Note H.

114.

We now proceed to speak of morbid and other extraordinary affections

of the retina, by which the eye may be susceptible of an appearance

of light without external light, reserving for a future occasion the

consideration of galvanic light.

115.

If the eye receives a blow, sparks seem to spread from it. In some

states of body, again, when the blood is heated, and the system much

excited, if the eye is pressed first gently, and then more and more

strongly, a dazzling and intolerable light may be excited.

116.

If those who have been recently couched experience pain and heat in the

eye, they frequently see fiery flashes and sparks: these symptoms last

sometimes for a week or fortnight, or till the pain and heat diminish.

117.

A person suffering from ear-ache saw sparks and balls of light in the

eye during each attack, as long as the pain lasted.

118.

Persons suffering from worms often experience extraordinary appearances

in the eye, sometimes sparks of fire, sometimes spectres of light,

sometimes frightful figures, which they cannot by an effort of the will

cease to see: sometimes these appearances are double.

119.

Hypochondriacs frequently see dark objects, such as threads, hairs,

spiders, flies, wasps. These appearances also exhibit themselves in the

incipient hard cataract. Many see semi-transparent small tubes, forms

like wings of insects, bubbles of water of various sizes, which fall

slowly down, if the eye is raised: sometimes these congregate together

so as to resemble the spawn of frogs; sometimes they appear as complete

spheres, sometimes in the form of lenses.

120.

As light appeared, in the former instances, without external light,

so also these images appear without corresponding external objects.

The images are sometimes transient, sometimes they last during

the patient's life. Colour, again, frequently accompanies these

impressions: for hypochondriacs often see yellow-red stripes in the

eye: these are generally more vivid and numerous in the morning, or

when lasting.

121.

We have before seen that the impression of any object may remain for a

time in the eye: this we have found to be a physiological phenomenon

(23): the excessive duration of such an impression, on the other band,

may be considered as morbid.

122.

The weaker the organ the longer the impression of the image lasts.

The retina does not so soon recover itself; and the effect may be

considered as a kind of paralysis (28).

123.

This is not to be wondered at in the case of dazzling lights. If any

one looks at the sun, he may retain the image in his eyes for several

days. Boyle relates an instance of ten years.

124.

The same takes place, in a certain degree, with regard to objects

that are not dazzling. Büsch relates of himself that the image of an

engraving, complete in all its parts, was impressed on his eye for

seventeen minutes.

125.

A person inclined to fulness of blood retained the image of a bright

red calico, with white spots, many minutes in the eye, and saw it float

before everything like a veil. It only disappeared by rubbing the eye

for some time.

126.

Scherfer observes that the red colour, which is the consequence of a

powerful impression of light, may last for some hours.

127.

As we can produce an appearance of light on the retina by pressure

on the eyeball, so by a gentle pressure a red colour appears, thus

corresponding with the after-image of an impression of light.

128.

Many sick persons, on awaking, see everything in the colour of the

morning sky, as if through a red veil: so, if in the evening they doze

and wake again, the same appearance presents itself. It remains for

some minutes, and always disappears if the eye is rubbed a little. Red

stars and balls sometimes accompany the impression. This state may last

for a considerable time.

129.

The aëronauts, particularly Zambeccari and his companions, relate

that they saw the moon blood-red at the highest elevation. As they

had ascended above the vapours of the earth, through which we see the

moon and sun naturally of such a colour, it may be suspected that this

appearance may be classed with the pathological colours. The senses,

namely, may be so influenced by an unusual state, that the whole

nervous system, and particularly the retina, may sink into a kind of

inertness and inexcitability. Hence it is not impossible that the moon

might act as a very subdued light, and thus produce the impression of

the red colour. The sun even appeared blood-red to the aëronauts of

Hamburgh.

If those who are at some elevation in a balloon scarcely hear each

other speak, may not this, too, be attributed to the inexcitable state

of the nerves as well as to the thinness of the air?

130.

Objects are often seen by sick persons in variegated colours. Boyle

relates an instance of a lady, who, after a fall by which an eye was

bruised, saw all objects, but especially white objects, glittering in

colours, even to an intolerable degree.

131.

Physicians give the name of "Chrupsia" to an affection of the sight,

occurring in typhoid maladies. In these cases the patients state that

they see the boundaries of objects coloured where light and dark meet.

A change probably takes place in the humours of the eye, through which

their achromatism is affected.

132.

In cases of milky cataract, a very turbid crystalline lens causes

the patient to see a red light. In a case of this kind, which was

treated by the application of electricity, the red light changed by

degrees to yellow, and at last to white, when the patient again began

to distinguish objects. These changes of themselves warranted the

conclusion that the turbid state of the lens was gradually approaching

the transparent state. We shall be enabled easily to trace this effect

to its source as soon as we become better acquainted with the physical

colours.

133.

If again it may be assumed that a jaundiced patient sees through

an actually yellow-coloured humour, we are at once referred to the

department of chemical colours, and it is thus evident that we can only

thoroughly investigate the chapter of pathological colours when we

have made ourselves acquainted with the whole range of the remaining

phenomena. What has been adduced may therefore suffice for the present,

till we resume the further consideration of this portion of our subject.

134.

In conclusion we may, however, at once advert to some peculiar states

or dispositions of the organ.

There are painters who, instead of rendering the colours of nature,

diffuse a general tone, a warm or cold hue, over the picture. In some,

again, a predilection for certain colours displays itself; in others a

want of feeling for harmony.

135.

Lastly, it is also worthy of remark, that savage nations, uneducated

people, and children have a great predilection for vivid colours;

that animals are excited to rage by certain colours; that people of

refinement avoid vivid colours in their dress and the objects that are

about them, and seem inclined to banish them altogether from their

presence.--Note I.

[1] It has been found necessary to follow the author's nomenclature

throughout--T.

[2] Non-perception of blue.

[3] It has not been thought necessary to copy the plates here referred

to.--T.