But just as a single ball seems to me double, if I touch it with my

fingers crossed--since my Understanding, at once reverting to the

cause and constructing it according to the laws of Space, takes for

granted that the fingers are in their normal position and of course

cannot do otherwise than attribute two spherical surfaces, which come

in contact with the outer sides of the first and middle fingers, to

two different balls--just so also does an object seem double, if my

eyes, instead of converging symmetrically and enclosing the optic

angle at a single point of the object, each view it at a different

inclination--in other words, if I squint. For the rays, which in this

case emanate from one point of the object, no longer impinge upon

those symmetrically corresponding points in both retinas with which

my mind has grown familiar by long experience, but upon other, quite

different ones which, in a symmetrical position of the eyes, could only

be affected in this way by different bodies; I therefore now see _two_

objects, precisely because perception takes place by means of, and

within, the Understanding.--The same thing happens without squinting

when, for instance, I look fixedly at the furthest of two objects

placed at unequal distances before me, and complete the optic angle at

it; for then the rays emanating from the nearer object do not impinge

upon symmetrically corresponding places in both retinas, wherefore my

Understanding attributes them to two objects, _i.e._ I see the nearer

object double (see fig. 2, page 70). If, on the contrary, I complete

the optic angle at the nearer object, by looking steadily at it, the

further object appears double. It is easy to test this by holding a

pencil two feet from the eyes, and looking alternately at it and at

some other more distant object behind it.

But the finest thing of all is, that this experiment may quite well be

reversed: so that, with two real objects straight before and close to

us, and with our eyes wide open, we nevertheless see but _one_. This is

the most striking proof that perception is a work of the Understanding

and by no means contained in sensation. Let two cardboard tubes, about

8 inches long and 1-1/2 inches in diameter, be fastened parallel to one

another, like those of a binocular telescope, and fix a shilling at the

end of each tube. On applying our eyes to the opposite extremity and

looking through the tubes, we shall see only _one_ shilling surrounded

by _one_ tube. For in this case the eyes being forced into a completely

parallel position, the rays emanating from the coins impinge exactly

upon the centres of the two retinas and those points which immediately

surround them, therefore upon places which correspond symmetrically

to each other; consequently the Understanding, taking for granted

the usual convergent position of the optic axes when objects are

near, admits but one object as the cause of the reflected rays. In

other words, we see but one object; so direct is the act of causal

apprehension in the Understanding.

We have not space enough here to refute one by one the physiological

explanations of single vision which have been attempted; but their

fallacy is shown by the following considerations:--

1^o. If seeing single were dependent upon an organic connection, the

corresponding points in both retinas, on which this phenomenon is shown

to depend, would correspond _organically_, whereas they do so in a

merely _geometrical_ sense, as has already been said. For, organically

speaking, the two inner and two outer corners of the eyes are those

which correspond, and so it is with the other parts also; whereas for

the purpose of single vision, it is the right side of the right retina

which corresponds to the right side of the left retina, and so on, as

the phenomena just described irrefutably show. It is also precisely on

account of the intellectual character of the process, that only the

most intelligent animals, such as the higher mammalia and birds of

prey--more especially owls--have their eyes placed so as to enable them

to direct both optic axes to the same point.

2^o. The hypothesis of a confluence or partial intersection of the

optic nerves before entering the brain, originated by Newton,[81] is

false, simply because it would then be impossible to see double by

squinting. Vesalius and Cæsalpinus besides have already brought forward

anatomical instances in which subjects saw single, although neither

fusion nor even contact of the optic nerves had taken place. A final

argument against the hypothesis of a mixed impression is supplied by

the fact, that on closing our right eye firmly and looking at the sun

with our left, the bright image which persists for a time is always in

the left, never in the right, eye: and _vice versa_.

[81] Newton, "Optics." Query 15.

The _third_ process by which the Understanding converts sensation into

perception, consists in constructing bodies out of the simple surfaces

hitherto obtained--that is, in adding the third dimension. This it

does by estimating the expansion of bodies in this third dimension

in Space--which is known to the Understanding _à priori_--through

Causality, according to the degree in which the eye is affected by the

objects, and to the gradations of light and shade. In fact, although

objects fill Space in all three dimensions, they can only produce

an impression upon the eye with two; for the nature of that organ

is such, that our sensation, in seeing, is merely planimetrical,

not stereometrical. All that is stereometrical in our perception is

added by the Understanding, which has for its sole data the direction

whence the eye receives its impression, the limits of that impression,

and the various gradations of light and dark: these data directly

indicate their causes, and enable us to distinguish whether what we

have before us is a disk or a ball. This mental process, like the

preceding ones, takes place so immediately and with such rapidity,

that we are conscious of nothing but the result. It is this which

makes perspective drawing so difficult a problem, that it can only

be solved by mathematics and has to be learnt; although all it has

to do, is to represent the sensation of seeing as it presents itself

to our Understanding as a datum for the third process: that is,

visual sensation in its merely planimetrical extension, to the _two_

dimensions of which extension, together with the said data in them, the

Understanding forthwith adds the _third_, in contemplating a drawing as

well as in contemplating reality. Perspective drawing is, in fact, a

sort of writing which can be read as easily as printed type, but which

few are able to write; precisely because our intellect, in perceiving,

only apprehends effects with a view to constructing their causes,

immediately losing sight of the former as soon as it has discovered

the latter. For instance, we instantly recognise a chair, whatever

position it may be in; while drawing a chair in any position belongs to

the art which abstracts from this third process of the Understanding,

in order to present the data alone for the spectator himself to

complete. In its narrowest acceptation, as we have already seen, this

is the art of drawing in perspective; in a more comprehensive sense,

it is the whole art of painting. A painting presents us with outlines

drawn according to the rules of perspective; lighter and darker places

proportioned to the effect of light and shade; finally patches of

colouring, which are determined as to quality and intensity by the

teaching of experience. This the spectator reads and interprets by

referring similar effects to their accustomed causes. The painter's art

consists in consciously retaining the data of visual sensation in the

artist's memory, as they are _before_ this third intellectual process;

while we, who are not artists, cast them aside without retaining them

in our memory, as soon as we have made use of them for the purpose

described above. We shall become still better acquainted with this

third intellectual process by now passing on to a fourth, which, from

its intimate connection with the third, serves to elucidate it.

This _fourth_ operation of the Understanding consists in acquiring

knowledge of the distance of objects from us: it is this precisely

which constitutes that third dimension of which we have been speaking.

Visual sensation, as we have said, gives us the _direction_ in which

objects lie, but not their _distance_ from us: that is, not their

_position_. It is for the _Understanding_ therefore to find out this

distance; or, in other words, the distance must be inferred from

purely _causal_ determinations. Now the most important of these is the

_visual angle_, which objects subtend; yet even this is quite ambiguous

and unable to decide anything by itself. It is like a word of double

meaning: the sense, in which it is to be understood, can only be

gathered from its connection with the rest. An object subtending the

same visual angle may in fact be small and near, or large and far off;

and it is only when we have previously ascertained its size, that the

visual angle enables us to recognise its distance: and conversely,

its size, when its distance is known to us. Linear perspective is

based upon the fact that the visual angle diminishes as the distance

increases, and its principles may here be easily deduced. As our sight

ranges equally in all directions, we see everything in reality as from

the interior of a hollow sphere, of which our eye occupies the centre.

Now in the first place, an infinite number of intersecting circles pass

through the centre of this sphere in all directions, and the angles

measured by the divisions of these circles are the possible angles

of vision. In the second place, the sphere itself modifies its size

according to the length of radius we give to it; therefore we may also

imagine it as consisting of an infinity of concentric, transparent

spheres. As all radii diverge, these concentric spheres augment in

size in proportion to their distance from us, and the degrees of their

sectional circles increase correspondingly: therefore the true size

of the objects which occupy them likewise increases. Thus objects are

larger or smaller according to the size of the spheres of which they

occupy similar portions--say 10°--while their visual angle remains

unchanged in both cases, leaving it therefore undecided, whether the

10° occupied by a given object belong to a sphere of 2 miles, or of

10 feet diameter. Conversely, if the size of the object has been

ascertained, the number of degrees occupied by it will diminish in

proportion to the distance and the size of the sphere to which we

refer it, and all its outlines will contract in similar proportion.

From this ensues the fundamental law of all perspective; for, as

objects and the intervals between them must necessarily diminish in

constant proportion to their distance from us, all their outlines

thereby contracting, the result will be, that with increasing distance,

what is above us will descend, what is below us will ascend, and all

that lies at our sides will come nearer together. This progressive

convergence, this linear perspective, no doubt enables us to estimate

distances, so far as we have before us an uninterrupted succession of

visibly connected objects; but we are not able to do this by means of

the visual angle alone, for here the help of another datum is required

by the Understanding, to act, in a sense, as commentary to the visual

angle, by indicating more precisely the share we are to attribute to

distance in that angle. Now there are four principal data of this kind,

which I am about to specify. Thanks to these data, even where there

is no linear perspective to guide us, if a man standing at a distance

of 200 feet appears to me subtending a visual angle twenty-four times

smaller than if he were only 2 feet off, I can nevertheless in most

cases estimate his size correctly. All this proves once more that

perception is not only a thing of the senses, but of the intellect

also.--I will here add the following special and interesting fact in

corroboration of what I have said about the basis of linear perspective

as well as about the intellectual nature of all perception. When I have

looked steadily at a coloured object with sharply defined outlines--say

a red cross--long enough for the physiological image to form in my

eye as a green cross, the further the surface on to which I project

it, the larger it will appear to me: and _vice versa_. For the image

itself occupies an unvarying portion of my retina, _i.e._ the portion

originally affected by the red cross; therefore when referred outwards,

or, in other words, recognised as the effect of an external object,

it forms an unchanging visual angle, say of 2°. Now if, in this case,

where all commentary to the visual angle is wanting, I remove it to

a distant surface, with which I necessarily identify it as belonging

to its effect, the cross will occupy 2° of a distant and therefore

larger sphere, and is consequently large. If, on the other hand, I

project the image on to a nearer object, it will occupy 2° of a smaller

sphere, and is therefore small. The resulting perception is in both

cases completely objective, quite like that of an external object;

and as it proceeds from an entirely subjective reason (from the image

having been excited in quite a different way), it thus confirms the

intellectual character of all objective perception.--This phenomenon

(which I distinctly remember to have been the first to notice, in 1815)

forms the theme of an essay by Séguin, published in the "_Comptes

rendus_" of the 2nd August, 1858, where it is served up as a new

discovery, all sorts of absurd and distorted explanations of it being

given. _Messieurs les illustres confrères_ let pass no opportunity for

heaping experiment upon experiment, the more complicated the better.

_Expérience!_ is their watchword; yet how rarely do we meet with any

sound, genuine reflection upon the phenomena observed! _Expérience!

expérience!_ followed by twaddle.

To return to the subsidiary data which act as commentaries to a given

visual angle, we find foremost among them the _mutationes oculi

internæ_, by means of which the eye adapts its refractory apparatus

to various distances by increasing and diminishing the refraction. In

what these modifications consist, has not yet been clearly ascertained.

They have been sought in the increased convexity, now of the _cornea_,

now of the crystalline _lens_; but the latest theory seems to me the

most probable one, according to which the lens is moved backwards

for distant vision and forwards for near vision, lateral pressure,

in the latter case, giving it increased protuberance; so that the

process would exactly resemble the mechanism of an opera-glass.

Kepler, however, had, in the main, already expressed this theory,

which may be found explained in A. Hueck's pamphlet, "Die Bewegung der

Krystallinse," 1841. If we are not clearly conscious of these inner

modifications of the eye, we have at any rate a certain feeling of

them, and of this we immediately avail ourselves to estimate distances.

As however these modifications are not available for the purposes of

clear sight beyond the range of from about 7 inches to 16 feet, the

Understanding is only able to apply this datum within those limits.

Beyond them, however, the second datum becomes available: that is to

say, the _optic angle_, formed by the two optic axes, which we had

occasion to explain when speaking of single vision. It is obvious

that this optic angle becomes smaller, the further the object is

removed: and _vice versa_. This different direction of the eyes, with

respect to each other, does not take place without producing a slight

sensation, of which we are nevertheless only in so far conscious as

the Understanding makes use of it, as a datum, in estimating distances

intuitively. By this datum we are not only enabled to cognize the

distance, but the precise position of the object viewed, by means of

the parallax of the eyes, which consists in each eye seeing the object

in a slightly different direction; so that if we close one eye, the

object seems to move. Thus it is not easy to snuff a candle with one

eye shut, because this datum is then wanting. But as the direction of

the eyes becomes parallel as soon as the distance of the object reaches

or exceeds 200 feet, and as the optic angle consequently then ceases to

exist, this datum only holds good within the said distance.

Beyond it, the Understanding has recourse to _atmospheric perspective_,

which indicates a greater distance by means of the increasing dimness

of all colours, of the appearance of physical blue in front of all dark

objects (according to Göthe's perfectly correct and true theory of

colours), and also of the growing indistinctness of all outlines. In

Italy, where the atmosphere is very transparent, this datum loses its

power and is apt to mislead: Tivoli, for instance, seems to be very

near when seen from Frascati. On the other hand, all objects appear

larger in a mist, which is an abnormal exaggeration of the datum;

because our Understanding assumes them to be further from us.

Finally, there remains the estimation of distance by means of the size

(known to us intuitively) of intervening objects, such as fields,

woods, rivers, &c. &c. This mode of estimation is only applicable where

there is uninterrupted succession: in other words, it can only be

applied to terrestrial, not to celestial objects. Moreover, we have in

general more practice in using it horizontally than vertically: a ball

on the top of a tower 200 feet high appears much smaller to us than

when lying on the ground 200 feet from us; because, in the latter case,

we estimate the distance more accurately. When we see human beings in

such a way, that what lies between them and ourselves is in a great

measure hidden from our sight, they always appear strikingly small.

The fact that our Understanding assumes everything it perceives in a

horizontal direction to be farther off, therefore larger, than what

is seen in a vertical direction, must partly be attributed to this

last mode of estimating distances, inasmuch as it only holds good when

applied horizontally and to terrestrial objects; but partly also to our

estimation of distances by atmospheric perspective, which is subject

to similar conditions. This is why the moon seems so much larger on

the horizon than at its zenith, although its visual angle accurately

measured--that is, the image projected by it on to the eye--is not at

all larger in one case than in the other; and this also accounts for

the flattened appearance of the vault of the sky: that is to say, for

its appearing to have greater horizontal than vertical extension. Both

phenomena therefore are purely intellectual or cerebral, not optical.

If it be objected, that even when at its zenith, the moon occasionally

has a hazy appearance without seeming to be larger, we answer, that

neither does it in that case appear red; for its haziness proceeds from

a greater density of vapours, and is therefore of a different kind from

that which proceeds from atmospheric perspective. To this may be added

what I have already said: that we only apply this mode of estimating

distances in a horizontal, not in a perpendicular, direction; besides,

in this case, other correctives come into play. It is related of

Saussure that, when on the Mont Blanc, he saw so enormous a moon rise,

that, not recognising what it was, he fainted with terror.

The properties of the telescope and magnifying glass, on the other

hand, depend upon a separate estimate according to the visual angle

alone: _i.e._, that of size by distance, and of distance by size;

because here the four other supplementary means of estimating distances

are excluded. The telescope in reality magnifies objects, while it

only seems to bring them nearer; because their size being known to us

empirically, we here account for its apparent increase by a diminution

of their distance from us. A house seen through a telescope, for

instance, seems to be ten times nearer, not ten times larger, than seen

with the naked eye. The magnifying glass, on the contrary, does not

really magnify, but merely enables us to bring the object nearer to

our eyes than would otherwise be possible; so that it only appears as

large as it would at that distance even without the magnifying glass.

In fact, we are prevented from seeing objects distinctly at less than

from eight to ten inches' distance from our eyes, by the insufficient

convexity of the ocular lens and cornea; but if we increase the

refraction by substituting the convexity of the magnifying glass for

that of the lens and cornea, we then obtain a clear image of objects

even when they are as near as half an inch from our eyes. Objects thus

seen in close proximity to us and in the size corresponding to that

proximity, are transferred by our Understanding to the distance at

which we naturally see distinctly, _i.e._ to about eight or ten inches

from our eyes, and we then estimate their magnitude according to this

distance and to the given visual angle.

I have entered thus fully into detail concerning all the different

processes by which seeing is accomplished, in order to show clearly

and irrefragably that the predominant factor in them is _the

Understanding_, which, by conceiving each change as an _effect_ and

referring that effect to its _cause_, produces the cerebral phenomenon

of the objective world on the basis of the _à priori_ fundamental

intuitions of Space and Time, for which it receives merely a few

data from the senses. And moreover the Understanding effects this

exclusively by means of its own peculiar form, the law of Causality;

therefore quite directly and intuitively, without any assistance

whatever from reflection--that is, from abstract knowledge by means of

conceptions and of language, which are the materials of _secondary_

knowledge, _i.e._ of _thought_, therefore of _Reason_.

That this knowledge through the Understanding is independent of

Reason's assistance, is shown even by the fact, that when, at any

time, the Understanding attributes a given effect to a wrong cause,

actually perceiving that cause, whereby _illusion_ arises, our Reason,

however clearly it may recognise _in abstracto_ the true state of

the matter, is nevertheless unable to assist the Understanding, and

the illusion persists undisturbed in spite of that better knowledge.

The above-mentioned phenomena of seeing and feeling double, which

result from an abnormal position of the organs of touch and sight,

are instances of such illusions; likewise the apparently increased

size of the rising moon; the image which forms in the focus of a

concave mirror and exactly resembles a solid body floating in space;

the painted relievo which we take for real; the apparent motion of a

shore or bridge on which we are standing, if a ship happens to pass

along or beneath it; the seeming proximity of very lofty mountains,

owing to the absence of atmospheric perspective, which is the result

of the purity of the air round their summits. In these and in a

multitude of similar cases, our Understanding takes for granted the

existence of the usual cause with which it is conversant and forthwith

perceives it, though our Reason has arrived at the truth by a different

road; for, the knowledge of the Understanding being anterior to that

of the Reason, the intellect remains inaccessible to the teaching

of the Reason, and thus the _illusion_--that is, the deception of

the Understanding--remains immovable; albeit _error_--that is, the

deception of the Reason--is obviated.--That which is correctly known by

the Understanding is _reality_: that which is correctly known by the

Reason is _truth_, or in other terms, a judgment having a sufficient

reason; _illusion_ (that which is wrongly perceived) we oppose to

_reality_: _error_ (that which is wrongly thought) to _truth_.

The purely formal part of empirical perception--that is, Space, Time,

and the law of Causality--is contained _à priori_ in the intellect;

but this is not the case with the application of this formal part to

empirical data, which has to be acquired by the Understanding through

practice and experience. Therefore new-born infants, though they

no doubt receive impressions of light and of colour, still do not

apprehend or indeed, strictly speaking, see objects. The first weeks of

their existence are rather passed in a kind of stupor, from which they

awaken by degrees when their Understanding begins to apply its function

to the data supplied by the senses, especially those of touch and

of sight, whereby they gradually gain consciousness of the objective

world. This newly-arising consciousness may be clearly recognised

by the look of growing intelligence in their eyes and a degree of

intention in their movements, especially in the smile with which they

show for the first time recognition of those who take care of them.

They may even be observed to make experiments for a time with their

sight and touch, in order to complete their apprehension of objects by

different lights, in different directions and at different distances:

thus pursuing a silent, but serious course of study, till they have

succeeded in mastering all the intellectual operations in seeing which

have been described. The fact of this schooling can be ascertained

still more clearly through those who, being born blind, have been

operated upon late in life, since they are able to give an account

of their impressions. Cheselden's blind man[82] was not an isolated

instance, and we find in all similar cases the fact corroborated,

that those who obtain their sight late in life, no doubt, see light,

outlines, and colours, as soon as the operation is over, but that they

have no objective perception of objects until their Understanding has

learnt to apply its causal law to data and to changes which are new

to it. On first beholding his room and the various objects in it,

Cheselden's blind man did not distinguish one thing from another; he

simply received the general impression of a totality all in one piece,

which he took for a smooth, variegated surface. It never occurred to

him to recognise a number of detached objects, lying one behind the

other at different distances. With blind people of this sort, it is by

the sense of touch, to which objects are already known, that they have

to be introduced to the sense of sight. In the beginning, the patient

has no appreciation whatever of distances and tries to lay hold of

everything. One, when he first saw his own house from outside, could

not conceive how so small a thing could contain so many rooms. Another

was highly delighted to find, some weeks after the operation, that the

engravings hanging on the walls of his room represented a variety of

objects. The "Morgenblatt" of October 23rd, 1817, contains an account

of a youth who was born blind, and obtained his sight at the age of

seventeen. He had to learn intelligent perception, for at first sight

he did not even recognise objects previously known to him through the

sense of touch. Every object had to be introduced to the sense of sight

by means of the sense of touch. As for the distances of the objects he

saw, he had no appreciation whatever of them, and tried to lay hold

indiscriminately of everything, far or near.--Franz expresses himself

as follows:[83]--

"A definite idea of distance, as well as of form and size, is

only obtained by sight and touch, and by reflecting on the

impressions made on both senses; but for this purpose we must

take into account the muscular motion and voluntary locomotion

of the individual.--Caspar Hauser, in a detailed account of his

own experience in this respect, states, that upon his first

liberation from confinement, whenever he looked through the

window upon external objects, such as the street, garden, &c.,

it appeared to him as if there were a shutter quite close to his

eye, and covered with confused colours of all kinds, in which he

could recognise or distinguish nothing singly. He says farther,

that he did not convince himself till after some time during his

walks out of doors, that what had at first appeared to him as a

shutter of various colours, as well as many other objects, were

in reality very different things; and that at length the shutter

disappeared, and he saw and recognised all things in their just

proportions. Persons born blind who obtain their sight by an

operation in later years only, sometimes imagine that all objects

touch their eyes, and lie so near to them that they are afraid

of stumbling against them; sometimes they leap towards the moon,

supposing that they can lay hold of it; at other times they run

after the clouds moving along the sky, in order to catch them,

or commit other such extravagancies. Since ideas are gained by

reflection upon sensation, it is further necessary in all cases,

in order that an accurate idea of objects may be formed from the

sense of sight, that the powers of the mind should be unimpaired,

and undisturbed in their exercise. A proof of this is afforded in

the instance related by Haslam,[84] of a boy who had no defect of

sight, but was weak in understanding, and who in his seventh year

was unable to estimate the distances of objects, especially as to

height; he would extend his hand frequently towards a nail on the

ceiling, or towards the moon, to catch it. It is therefore the

judgment which corrects and makes clear this idea, or perception

of visible objects."

[82] See the original report in vol. 35 of the "Philosophical

Transactions" as to this case.

[83] Franz, "The Eye, a treatise on preserving this organ in a

healthy state and improving the sight." London, Churchill, 1839,

pp. 34-36.

[84] Haslam's "Observations on Madness and Melancholy," 2nd ed. p.

192.

The intellectual nature of perception as I have shown it, is

corroborated physiologically by Flourens[85] as follows:

"Il faut faire une grand distinction entre les sens et

l'intelligence. L'ablation d'un tubercule détermine la perte

de la _sensation_, du _sens_ de la vue; la rétine devient

insensible, l'iris devient immobile. L'ablation d'un lobe

cérébral laisse la _sensation_, le _sens_, la _sensibilité_

de la rétine, la _mobilité_ de l'iris; elle ne détruit que la

_perception_ seule. Dans un cas, c'est un fait _sensorial_; et,

dans l'autre, un fait _cérébral_; dans un cas, c'est la perte

du _sens_; dans l'autre, c'est la perte de la _perception_. La

distinction des perceptions et des sensations est encore un grand

résultat; et it est démontré aux yeux. Il y a deux moyens de

faire perdre la vision par l'encéphale: 1° par les tubercules,

c'est la perte du sens, de la sensation; 2° par les lobes, c'est

la perte de la perception, de l'intelligence. La sensibilité

n'est donc pas l'intelligence; penser n'est donc pas sentir; et

voilà toute une philosophie renversée. L'idée n'est donc pas

la sensation; et voilà encore une autre preuve du vice radical

de cette philosophie." And again, p. 77, under the heading:

Séparation de la Sensibilité et de la Perception:--"Il y a une

de mes expériences qui sépare nettement la _sensibilité_ de

la _perception_. Quand on enlève le _cerveau proprement dit_

(_lobes_ ou _hémisphères cérébraux_) à un animal, l'animal

perd la vue. Mais, par rapport a l'œil, rien n'est changé: les

objets continuent à se peindre sur la rétine; l'_iris_ reste

contractile, le _nerf optique_ sensible, parfaitement sensible.

Et cependant l'animal ne voit plus; il n'y a plus _vision_,

quoique tout ce qui est _sensation_ subsiste; il n'y a plus

_vision_, parce qu'il n'y a plus _perception_. Le _percevoir_, et

non le _sentir_, est donc le premier élément de l'_intelligence_.

La _perception_ est partie de l'_intelligence_, car elle se

perd avec l'_intelligence_, et par l'ablation du même organe,

les _lobes_ ou _hémisphères cérébraux_; et la _sensibilité_

n'en est point partie, puisqu'elle subsiste après la perte de

l'_intelligence_ et l'ablation des _lobes_ ou _hémisphères_."

[85] Flourens, "De la vie et de l'Intelligence," 2nd edition,

Paris, Garnier Frères, 1852, p. 49.

The following famous verse of the ancient philosopher Epicharmus,

proves that the ancients in general recognized the intellectual

nature of perception: Νοῦς ὁρῇ καὶ νοῦς ἀκούει· τἆλλα κωφὰ καὶ τυφλά.

(_Mens videt, mens audit; cætera surda et cœca._)[86] Plutarch in

quoting this verse, adds:[87] ὡς τοῦ περὶ τὰ ὄμματα καὶ ὦτα πάθους,

ἂν μὴ παρῇ τὸ φρονοῦν, αἴσθησιν οὐ ποιοῦντος (_quia affectio oculorum

et aurium nullum affert sensum, intelligentia absente_). Shortly

before too he says: Στράτωνος τοῦ φυσικοῦ λόγος ἐστίν, ἀποδεικνύων

ὡς οὐδ' αἰσθάνεσθαι τοπαράπαν ἄνευ τοῦ νοεῖν ὑπάρχει. (_Stratonis

physici exstat ratiocinatio, qua "sine intelligentia sentiri omnino

nihil posse" demonstrat._)[88] Again shortly after he says: ὅθεν

ἀνάγκη, πᾶσιν, οἷς τὸ αἰσθάνεσθαι, καὶ τὸ νοεῖν ὑπάρχειν, εἰ τῷ νοεῖν

αἰσθάνεσθαι πεφύκαμεν (_quare necesse est, omnia, quæ sentiunt, etiam

intelligere, siquidem intelligendo demum sentiamus_).[89] A second

verse of Epicharmus might be connected with this, which is quoted by

Diogenes Laertes (iii. 16):

Εὔμαιε, τὸ σοφόν ἐστιν οὐ καθ' ἓν μόνον,

ἀλλ' ὅσα περ ζῇ, πάντα καὶ γνώμαν ἔχει.

[86] "It is the mind that sees and hears; all besides is deaf and

blind." (Tr. Ad.)

[87] Plutarch, "De solert. animal." c. 3. "For the affection of

our eyes and ears does not produce any perception, unless it be

accompanied by thought." (Tr. Ad.)

[88] "Straton, the physicist, has proved that 'without thinking it

is quite impossible to perceive.'" (Tr. Ad.)

[89] "Therefore it is necessary that all who perceive should also

think, since we are so constituted as to perceive by means of

thinking." (Tr. Ad.)

(_Eumaee, sapientia non uni tantum competit, sed quæcunque vivunt etiam

intellectum habent._) Porphyry likewise endeavours to show at length

that all animals have understanding.[90]

[90] Porph. "De abstinentia," iii. 21.

Now, that it should be so, follows necessarily from the intellectual

character of perception. All animals, even down to the very lowest,

must have Understanding--that is, knowledge of the causal law,

although they have it in very different degrees of delicacy and of

clearness; at any rate they must have as much of it as is required

for perception by their senses; for sensation without Understanding

would be not only a useless, but a cruel gift of Nature. No one, who

has himself any intelligence, can doubt the existence of it in the

higher animals. But at times it even becomes undeniably evident that

their knowledge of causality is actually _à priori_, and that it does

not arise from the habit of seeing one thing follow upon another. A

very young puppy will not, for instance, jump off a table, because

he foresees what would be the consequence. Not long ago I had some

large curtains put up at my bed-room window, which reached down to the

floor, and were drawn aside from the centre by means of a string. The

first morning they were opened I was surprised to see my dog, a very

intelligent poodle, standing quite perplexed, and looking upwards and

sidewards for the cause of the phenomenon: that is, he was seeking

for the change which he knew _à priori_ must have taken place. Next

day the same thing happened again.--But even the lowest animals have

perception--consequently Understanding--down to the aquatic polypus,

which has no distinct organs of sensation, yet wanders from leaf to

leaf on its waterplant, while clinging to it with its feelers, in

search of more light.

Nor is there, indeed, any difference, beyond that of degree, between

this lowest Understanding and that of man, which we however distinctly

separate from his Reason. The intermediate gradations are occupied by

the various series of animals, among which the highest, such as the

monkey, the elephant, the dog, astonish us often by their intelligence.

But in every case the business of the Understanding is invariably to

apprehend directly causal relations: first, as we have seen, those

between our own body and other bodies, whence proceeds objective

perception; then those between these objectively perceived bodies among

themselves, and here, as has been shown in § 20, the causal relation

manifests itself in three forms--as cause, as stimulus, and as motive.

All movement in the world takes place according to these three forms

of the causal relation, and through them alone does the intellect

comprehend it. Now, if, of these three, _causes_, in the narrowest

sense of the word, happen to be the object of investigation for

the Understanding, it will produce Astronomy, Mechanics, Physics,

Chemistry, and will invent machines for good and for evil; but in all

cases a direct, intuitive apprehension of the causal connection will

in the last resort lie at the bottom of all its discoveries. For the

sole form and function of the Understanding is this apprehension, and

not by any means the complicated machinery of Kant's twelve Categories,

the nullity of which I have proved.--(All comprehension is a direct,

consequently intuitive, apprehension of the causal connection; although

this has to be reduced at once to abstract conceptions in order to

be fixed. To calculate therefore, is not to understand, and, in

itself, calculation conveys no comprehension of things. Calculation

deals exclusively with abstract conceptions of magnitudes, whose

mutual relations it determines. By it we never attain the slightest

comprehension of a physical process, for this requires _intuitive_

comprehension of space-relations, by means of which causes take

effect. Calculations have merely practical, not theoretical, value. It

may even be said that _where calculation begins, comprehension ceases_;

for a brain occupied with numbers is, as long as it calculates,

entirely estranged from the causal connection in physical processes,

being engrossed in purely abstract, numerical conceptions. The result,

however, only shows us _how much_, never _what_. "_L'expérience et le

calcul_," those watchwords of French physicists, are not therefore by

any means adequate [for thorough insight].)--If, again, _stimuli_ are

the guides of the Understanding, it will produce Physiology of Plants

and Animals, Therapeutics, and Toxicology. Finally, if it devotes

itself to the study of _motives_, the Understanding will use them,

on the one hand, theoretically, to guide it in producing works on

Morality, Jurisprudence, History, Politics, and even Dramatic and Epic

Poetry; on the other hand, practically, either merely to train animals,

or for the higher purpose of making human beings dance to its music,

when once it has succeeded in discovering which particular wire has

to be pulled in order to move each puppet at its pleasure. Now, with

reference to the function which effects this, it is quite immaterial

whether the intellect turns gravitation ingeniously to account, and

makes it serve its purpose by stepping in just at the right time, or

whether it brings the collective or the individual propensities of men

into play for its own ends. In its practical application we call the

Understanding _shrewdness_ or, when used to outwit others, _cunning_;

when its aims are very insignificant, it is called _slyness_ and, if

combined with injury to others, _craftiness_. In its purely theoretical

application, we call it simply _Understanding_, the higher degrees of

which are named _acumen_, _sagacity_, _discernment_, _penetration_,

while its lower degrees are termed _dulness_, _stupidity_, _silliness_,

&c. &c. These widely differing degrees of sharpness are innate, and

cannot be acquired; although, as I have already shown, even in the

earliest stages of the application of the Understanding, _i.e._ in

empirical perception, practice and knowledge of the material to which

it is applied, are needed. Every simpleton has Reason--give him

the premisses, and he will draw the conclusion; whereas _primary_,

consequently intuitive, knowledge is supplied by the Understanding:

herein lies the difference. The pith of every great discovery, of every

plan having universal historical importance, is accordingly the product

of a happy moment in which, by a favourable coincidence of outer and

inner circumstances, some complicated causal series, some hidden causes

of phenomena which had been seen thousands of times before, or some

obscure, untrodden paths, suddenly reveal themselves to the intellect.--

By the preceding explanations of the processes in seeing and feeling,

I have incontestably shown that empirical perception is essentially

the work of _the Understanding_, for which the material only is

supplied by the senses in sensation--and a poor material it is, on the

whole; so that _the Understanding_ is, in fact, the artist, while the

senses are but the under-workmen who hand it the materials. But the

process consists throughout in referring from given effects to their

causes, which by this process are enabled to present themselves as

objects in Space. The very fact that we presuppose Causality in this

process, proves precisely that this law must have been supplied by

the Understanding itself; for it could never have found its way into

the intellect from outside. It is indeed the first condition of all

empirical perception; but this again is the form in which all external

experience presents itself to us; how then can this law of Causality be

derived from experience, when it is itself essentially presupposed by

experience?--It was just because of the utter impossibility of this,

and because Locke's philosophy had put an end to all _à priority_,

that Hume denied the whole reality of the conception of Causality.

He had besides already mentioned two false hypotheses in the seventh

section of his "Inquiry concerning the Human Understanding," which

recently have again been advanced: the one, that the effect of the will

upon the members of our body; the other, that the resistance opposed

to our pressure by outward objects, is the origin and prototype of

the conception of Causality. Hume refutes both in his own way and

according to his own order of ideas. I argue as follows. There is

no causal connection whatever between acts of the will and actions

of the body; on the contrary, both are immediately one and the same

thing, only perceived in a double aspect--that is, on the one hand,

in our self-consciousness, or inner sense, as acts of the will; on

the other, simultaneously in exterior, spacial brain-perception,

as actions of the body.[91] The second hypothesis is false, first

because, as I have already shown at length, a mere sensation of touch

does not yet give any objective perception whatever, let alone the

conception of Causality, which never can arise from the feeling of an

impeded muscular effort: besides impediments of this kind often occur

without any external cause; secondly, because our pressing against an

external object necessarily has a motive, and this already presupposes

apprehension of that object, which again presupposes knowledge of

Causality.--But the only means of radically proving the conception of

Causality to be independent of all experience was by showing, as I have

done, that the whole possibility of experience is conditioned by the

conception of Causality. In § 23 I intend to show that Kant's proof,

propounded with a similar intent, is false.

[91] Compare "Die Welt a. W. u. V." 3rd edition, vol. ii. p. 41.

[The 3rd edition of "Die Welt a. W. u. V." contains at this place

a supplement which is wanting in the 2nd edition, vol. ii. p.

38.--Note by the Editor of the 3rd edition.]

This is also the proper place for drawing attention to the fact,

that Kant either did not clearly recognise in empirical perception

the mediation of the causal law--which law is known to us before all

experience--or that he intentionally evaded mentioning it, because

it did not suit his purpose. In the "Critique of Pure Reason," for

instance, the relation between causality and perception is not treated

in the "Doctrine of Elements," but in the chapter on the "Paralogisms

of Pure Reason," where one would hardly expect to find it; moreover it

appears in his "Critique of the Fourth Paralogism of Transcendental

Psychology," and only in the first edition.[92] The very fact that

this place should have been assigned to it, shows that in considering

this relation, he always had the transition from the phenomenon to

the thing in itself exclusively in view, but not the genesis of

perception itself. Here accordingly he says that the existence of a

real external object is not given directly in perception, but can be

added to it in thought and thus inferred. In Kant's eyes, however,

he who does this is a Transcendental Realist, and consequently on a

wrong road. For by his "outward object" Kant here means the thing in

itself. The Transcendental Idealist, on the contrary, stops short at

the perception of something empirically real--that is, of something

existing outside us in Space--without needing the inference of a cause

to give it reality. For _perception_, according to Kant, is quite

directly accomplished without any assistance from the causal nexus, and

consequently from the Understanding: he simply identifies perception

with sensation. This we find confirmed in the passage which begins,

"With reference to the reality of external objects, I need as little

trust to inference," &c. &c.[93] and again in the sentence commencing

with "Now we may well admit," &c. &c.[94] It is quite clear from these

passages that perception of external things in Space, according to

Kant, precedes all application of the causal law, therefore that the

causal law does not belong to perception as an element and condition

of it: for him, mere sensation is identical with perception. Only in

as far as we ask what may, in a _transcendental_ sense, exist _outside

of us_: that is, when we ask for the thing in itself, is Causality

mentioned as connected with perception. Moreover Kant admits the

existence, nay, the mere possibility, of causality only in reflection:

that is, in abstract, distinct knowledge by means of conceptions;

therefore he has no suspicion that its application is _anterior to all

reflection_, which is nevertheless evidently the case, especially in

empirical, sensuous perception which, as I have proved irrefragably

in the preceding analysis, could never take place otherwise. Kant

is therefore obliged to leave the genesis of empirical perception

unexplained. With him it is a mere matter of the senses, given as it

were in a miraculous way: that is, it coincides with sensation. I

should very much like my reflective readers to refer to the passages I

have indicated in Kant's work, in order to convince themselves of the

far greater accuracy of my view of the whole process and connection.

Kant's extremely erroneous view has held its ground till now in

philosophical literature, simply because no one ventured to attack it;

therefore I have found it necessary to clear the way in order to throw

light upon the mechanism of our knowledge.

[92] Kant, "Krit. d. r. V." 1st edition, p. 367 _sqq._ (English

translation by M. Müller, p. 318 _sqq._)

[93] Kant, "Krit. d. r. Vern." 1st edition, p. 371. (English

translation, by M. Müller, p. 322.)

[94] Kant, "Krit. d. r. Vern." 1st edition, p. 372. (English

translation, p. 323.)

Kant's fundamental idealistic position loses nothing whatever, nay, it

even gains by this rectification of mine, in as far as, with me, the

necessity of the causal law is absorbed and extinguished in empirical

perception as its product and cannot therefore be invoked in behalf

of an entirely transcendent question as to the thing in itself. On

referring to my theory above concerning empirical perception, we find

that its first datum, sensation, is absolutely subjective, being a

process within the organism, because it takes place beneath the skin.

Locke has completely and exhaustively proved, that the feelings of

our senses, even admitting them to be roused by external causes,

cannot have any resemblance whatever to the qualities of those causes.

Sugar, for instance, bears no resemblance at all to sweetness, nor

a rose to redness. But that they should need an external cause at

all, is based upon a law whose origin lies demonstrably within us,

in our brain; therefore this necessity is not less subjective than

the sensations themselves. Nay, even _Time_--that primary condition

of every possible _change_, therefore also of the change which first

permits the application of the causal law--and not less _Space_--which

alone renders the externalisation of causes possible, after which they

present themselves to us as objects--even Time and Space, we say, are

subjective forms of the intellect, as Kant has conclusively proved.

Accordingly we find all the elements of empirical perception lying

within us, and nothing contained in them which can give us reliable

indications as to anything differing absolutely from ourselves,

anything in itself.--But this is not all. What we think under the

conception _matter_, is the residue which remains over after bodies

have been divested of their shape and of all their specific qualities:

a residue, which precisely on that account must be identical in all

bodies. Now these shapes and qualities which have been abstracted by

us, are nothing but the peculiar, specially defined _way in which

these bodies act_, which constitutes precisely their difference. If

therefore we leave these shapes and qualities out of consideration,

there remains nothing but _mere activity in general_, pure action as

such, Causality itself, objectively thought--that is, the reflection

of our own Understanding, the externalised image of its sole function;

and Matter is throughout pure Causality, its essence is Action in

general.[95] This is why pure Matter cannot be perceived, but can only

be thought: it is a something we add to every reality, as its basis, in

thinking it. For pure Causality, mere action, without any defined mode

of action, cannot become perceptible, therefore it cannot come within

any experience.--Thus Matter is only the objective correlate to pure

Understanding; for it is Causality in general, and nothing else: just

as the Understanding itself is direct knowledge of cause and effect,

and nothing else. Now this again is precisely why the law of causality

is not applicable to Matter itself: that is to say, Matter has neither

beginning nor end, but is and remains permanent. For as, on the one

hand, Causality is the indispensable condition of all alternation in

the accidents (forms and qualities) of Matter, _i.e._ of all passage

in and out of being; but as, on the other hand, Matter is pure

Causality itself, as such, objectively viewed: it is unable to exercise

its own power upon itself, just as the eye can see everything but

itself. "Substance" and Matter being moreover identical, we may call

_Substance_, _action_ viewed _in abstracto_: _Accidents_, particular

modes of action, action _in concreto_.--Now these are the results to

which true, _i.e._ transcendental, Idealism leads. In my chief work I

have shown that the thing in itself--_i.e._ whatever, on the whole,

exists independently of our representation--cannot be got at by way of

representation, but that, to reach it, we must follow quite a different

path, leading through the inside of things, which lets us into the

citadel, as it were, by treachery.--

[95] Compare "Die Welt a. W. u. V." 2nd edition; vol. i. sect. 4,

p. 9; and vol. ii. pp. 48, 49 (3rd edition, vol. i. p. 10; vol. ii.

p. 52). English translation, vol. i. pp. 9-10; vol. ii. p. 218.

But it would be downright chicanery, nothing else, to try and

compare, let alone identify, such an honest, deep, thorough analysis

of empirical perception as the one I have just given, which proves all

the elements of perception to be subjective, with Fichte's algebraic

equations of the _Ego_ and the _Non-Ego_; with his sophistical

pseudo-demonstrations, which in order to be able to deceive his readers

had to be clothed in the obscure, not to say absurd, language adopted

by him; with his explanations of the way in which the _Ego_ spins

the _Non-Ego_ out of itself; in short, with all the buffoonery of

scientific emptiness.[96] Besides, I protest altogether against any

community with this Fichte, as Kant publicly and emphatically did in a

notice _ad hoc_ in the "Jenaer Litteratur Zeitung."[97] Hegelians and

similar ignoramuses may continue to hold forth to their heart's content

upon Kant-Fichteian philosophy: there exists a Kantian philosophy and

a Fichteian hocus-pocus,--this is the true state of the case, and will

remain so, in spite of those who delight in extolling what is bad and

in decrying what is good, and of these Germany possesses a larger

number than any other country.

[96] _Wissenschaftsleere_ (literally, _emptiness of science_), a

pun of Schopenhauer's on the title of Fichte's _Wissenschaftslehre_

(_doctrine of science_), which cannot be rendered in English.

(Tr.'s Note.)

[97] Kant, "Erklärung über Fichte's Wissenschaftslehre." See the

"Intelligenzblatt" of the Jena Literary Gazette (1799), No. 109.

§ 22. _Of the Immediate Object._

Thus it is from the sensations of our body that we receive the data for

the very first application of the causal law, and it is precisely by

that application that the perception of this class of objects arises.

They therefore have their essence and existence solely in virtue of the

intellectual function thus coming into play, and of its exercise.

Now, as far as it is the starting-point, _i.e._ the mediator, for our

perception of all other objects, I have called the bodily organism,

in the first edition of the present work, the _Immediate Object_;

this, however, must not be taken in a strictly literal sense. For

although our bodily sensations are all apprehended directly, still this

immediate apprehension does not yet make our body itself perceptible

to us as an object; on the contrary, up to this point all remains

subjective, that is to say, sensation. From this sensation certainly

proceeds the perception of all other objects as the causes of such

sensations, and these causes then present themselves to us as objects;

but it is not so with the body itself, which only supplies sensations

to consciousness. It is only _indirectly_ that we know even this

body objectively, _i.e._ as an object, by its presenting itself,

like all other objects, as the recognised cause of a subjectively

given effect--and precisely on this account _objectively_--in our

Understanding, or brain (which is the same). Now this can only take

place when its own senses are acted upon by its parts: for instance,

when the body is seen by the eye, or felt by the hand, &c., upon which

data the brain (or understanding) forthwith constructs it as to shape

and quality in space.--The immediate presence in our consciousness of

representations belonging to this class, depends therefore upon the

position assigned to them in the causal chain--by which all things

are _connected_--relatively to the body (for the time being) of the

Subject--by which (the Subject) all things are _known_.

§ 23. _Arguments against Kant's Proof of the_ à priority _of the

conception of Causality_.

One of the chief objects of the "Critique of Pure Reason" is to show

the universal validity, for all experience, of the causal law, its _à

priority_, and, as a necessary consequence of this, its restriction to

possible experience. Nevertheless, I cannot assent to the proof there

given of the _à priority_ of the principle, which is substantially

this:--"The _synthesis_ of the manifold by the imagination, which

is necessary for all empirical knowledge, gives succession, but not

yet determinate succession: that is, it leaves undetermined which of

two states perceived was the first, not only in my imagination, but

in the object itself. But definite order in this succession--through

which alone what we perceive becomes experience, or, in other words,

authorizes us to form objectively valid judgments--is first brought

into it by the purely intellectual conception of cause and effect.

Thus the principle of causal relation is the condition which renders

experience possible, and, as such, it is given us _à priori_."[98]

[98] Kant, "Krit. d. r. Vern." 1st edition, p. 201; 5th edition, p.

246. (English translation by M. Müller, p. 176.) This is, however,

not a literal quotation. (Tr.'s note.)

According to this, the order in which changes succeed each other in

real objects becomes known to us as objective only by their causality.

This assertion Kant repeats and explains in the "Critique of Pure

Reason," especially in his "Second Analogy of Experience,"[99] and

again at the conclusion of his "Third Analogy," and I request every

one who desires to understand what I am now about to say, to read

these passages. In them he affirms everywhere that _the objectivity

of the succession of representations_--which he defines as their

correspondence with the succession of real objects--is only known

through the rule by which they follow upon one another: that is,

through the law of causality; that my mere apprehension consequently

leaves the objective relation between phenomena following one another

quite undetermined: since I merely apprehend the succession of my

own representations, but the succession in my apprehension does not

authorize me to form any judgment whatever as to the succession in

the object, unless that judgment be based upon causality; and since,

besides, I might invert the order in which these perceptions follow

each other in my apprehension, there being nothing which determines

them as objective. To illustrate this assertion, Kant brings forward

the instance of a house, whose parts we may consider in any order we

like, from top to bottom, or from bottom to top; the determination of

succession being in this case purely subjective and not founded upon

an object, because it depends upon our pleasure. In opposition to this

instance, he brings forward the perception of a ship sailing down a

river, which we see successively lower and lower down the stream, which

perception of the successively varying positions of the ship cannot be

changed by the looker-on. In this latter case, therefore, he derives

the subjective following in his own apprehension from the objective

following in the phenomenon, and on this account he calls it an

_event_. Now I maintain, on the contrary, that _there is no difference

at all between these two cases, that both are events_, and that our

knowledge of both is objective: that is to say, it is knowledge of

changes in real objects recognized as such by the Subject. _Both are

changes of relative position in two bodies._ In the first case, one of

these bodies is a part of the observer's own organism, the eye, and the

other is the house, with respect to the different parts of which the

eye successively alters its position. In the second, it is the ship

which alters its position towards the stream; therefore the change

occurs between two bodies. Both are events, the only difference being

that, in the first, the change has its starting-point in the observer's

own body, from whose sensations undoubtedly all his perceptions

originally proceed, but which is nevertheless an object among objects,

and in consequence obeys the laws of the objective, material world.

For the observer, as a purely cognising individual, any movement of

his body is simply an empirically perceived fact. It would be just as

possible in the second as in the first instance, to invert the order of

succession in the change, were it as easy for the observer to move the

ship up the stream as to alter the direction of his own eyes. For Kant

infers the successive perception of different parts of the house to be

neither objective nor an event, because it depends upon his own will.

But the movement of his eyes in the direction from roof to basement

is one event, and in the direction from basement to roof another

event, just as much as the sailing of the ship. There is no difference

whatever here, nor is there any difference either, as to their being

or not being events, between my passing a troop of soldiers and their

passing me. If we fix our eyes on a ship sailing close by the shore on

which we are standing, it soon seems as if it were the ship that stood

still and the shore that moved. Now, in this instance we are mistaken,

it is true, as to the cause of the relative change of position, since

we attribute it to a wrong cause; the real succession in the relative

positions of our body towards the ship is nevertheless quite rightly

and objectively recognised by us. Even Kant himself would not have

believed that there was any difference, had he borne in mind that his

own body was an object among objects, and that the succession in his

empirical perceptions depended upon the succession of the impressions

received from other objects by his body, and was therefore an objective

succession: that is to say, one which takes place among objects

_directly_ (if not indirectly) and independently of the will of the

Subject, and which may therefore be quite well recognised without any

causal connection between the objects acting successively on his body.

[99] _Ibid._ p. 189 of the 1st edition; more fully, p. 232 of the

5th edition. (English translation by M. Müller, p. 166.)

Kant says, Time cannot be perceived; therefore no succession of

representations can be empirically perceived as objective: _i.e._ can

be distinguished as changes in phenomena from the changes of mere

subjective representations. The causal law, being a rule according

to which states follow one another, is the only means by which the

objectivity of a change can be known. Now, the result of his assertion

would be, that no succession in Time could be perceived by us as

objective, excepting that of cause and effect, and that every other

succession of phenomena we perceive, would only be determined so, and

not otherwise, by our own will. In contradiction to all this I must

adduce the fact, that it is quite possible for phenomena to _follow

upon_ one another without _following from_ one another. Nor is the law

of causality by any means prejudiced by this; for it remains certain

that each change is the effect of another change, this being firmly

established _à priori_; only each change not only follows upon the

single one which is its cause, but upon all the other changes which

occur simultaneously with that cause, and with which that cause stands

in no causal connection whatever. It is not perceived by me exactly

in the regular order of causal succession, but in quite a different

order, which is, however, no less objective on that account, and

which differs widely from any subjective succession depending on my

caprice, such as, for instance, the pictures of my imagination. The

succession, in Time, of events which stand in no causal connection with

each other is precisely what we call _contingency_.[100] Just as I am

leaving my house, a tile happens to fall from the roof which strikes

me; now, there is no causal connection whatever between my going out

and the falling of the tile; yet the order of their succession--that

is, that my going out preceded the falling of the tile--is objectively

determined in my apprehension, not subjectively by my will, by which

that order would otherwise have most likely been inverted. The order

in which tones follow each other in a musical composition is likewise

objectively determined, not subjectively by me, the listener; yet

who would think of asserting that musical tones follow one another

according to the law of cause and effect? Even the succession of day

and night is undoubtedly known to us as an objective one, but we as

certainly do not look upon them as causes and effects of one another;

and as to their common cause, the whole world was in error till

Copernicus came; yet the correct knowledge of their succession was not

in the least disturbed by that error. Hume's hypothesis, by the way,

also finds its refutation through this; since the following of day and

night upon each other--the most ancient of all successions and the one

least liable to exception--has never yet misled anyone into taking them

for cause and effect of each other.

[100] In German _Zufall_, a word derived from the _Zusammenfallen_

(falling together), _Zusammentreffen_ (meeting together), or

coinciding of what is unconnected, just as τὸ συμβεβηκός from

συμβαίνειν. (Compare Aristotle, "Anal. post.," i. 4.)

Elsewhere Kant asserts, that a representation only shows reality

(which, I conclude, means that it is distinguished from a mere

mental image) by our recognising its necessary connection with other

representations subject to rule (the causal law) and its place in a

determined order of the time-relations of our representations. But

of how few representations are we able to know the place assigned to

them by the law of causality in the chain of causes and effects! Yet

we are never embarrassed to distinguish objective from subjective

representations: real, from imaginary objects. When asleep, we are

unable to make this distinction, for our brain is then isolated from

the peripherical nervous system, and thereby from external influences.

In our dreams therefore, we take imaginary for real things, and it is

only when we awaken: that is, when our nervous sensibility, and through

this the outer world, once more comes within our consciousness, that we

become aware of our mistake; still, even in our dreams, so long as they

last, the causal law holds good, only an impossible material is often

substituted for the usual one. We might almost think that Kant was

influenced by Leibnitz in writing the passage we have quoted, however

much he differs from him in all the rest of his philosophy; especially

if we consider that Leibnitz expresses precisely similar views, when,

for instance, he says: "La vérité des choses sensibles ne consiste que

dans la liaison des phénomènes, qui doit avoir sa raison, et c'est

ce qui les distingue des songes. ---- Le vrai Critérion, en matière

des objets des sens, est la liaison des phénomènes, qui garantit les

vérités de fait, à l'egard des choses sensibles hors de nous."[101]

[101] Leibnitz, "Nouveaux Essais sur l'Entendement," lib. iv. ch.

ii. sect. 14.

It is clear that in proving the _à priority_ and the necessity of the

causal law by the fact that the objective succession of changes is

known to us only by means of that law, and that, in so far, causality

is a condition for all experience, Kant fell into a very singular

error, and one which is indeed so palpable, that the only way we can

account for it is, by supposing him to have become so absorbed in the

_à priori_ part of our knowledge, that he lost sight of what would have

been evident to anyone else. The only correct demonstration of the _à

priority_ of the causal law is given by me in § 21 of the present work.

That _à priority_ finds its confirmation every moment in the infallible

security with which we expect experience to tally with the causal

law: that is to say, in the apodeictic certainty we ascribe to it, a

certainty which differs from every other founded on induction--the

certainty, for instance, of empirically known laws of Nature--in

that we can conceive no exception to the causal law anywhere within

the world of experience. We can, for instance, _conceive_ that in an

exceptional case the law of gravitation might cease to act, but not

that this could happen without a cause.

Kant and Hume have fallen into opposite errors in their proofs. Hume

asserts that all _consequence_ is mere _sequence_; whereas Kant

affirms that all _sequence_ must necessarily be _consequence_. Pure

Understanding, it is true, can only conceive _consequence_ (causal

result), and is no more able to conceive mere _sequence_ than to

conceive the difference between right and left, which, like sequence,

is only to be grasped by means of pure Sensibility. Empirical knowledge

of the following of events in Time is, indeed, just as possible as

empirical knowledge of juxtaposition of things in Space (this Kant

denies elsewhere), but _the way in which_ things follow _upon_ one

another in general in Time can no more be explained, than the way in

which one thing follows _from_ another (as the effect of a cause):

the former knowledge is given and conditioned by pure Sensibility;

the latter, by pure Understanding. But in asserting that knowledge

of the objective succession of phenomena can only be attained by

means of the causal law, Kant commits the same error with which

he reproaches Leibnitz:[102] that of "intellectualising the forms

of Sensibility."--My view of succession is the following one. We

derive our knowledge of the bare _possibility_ of succession from

the form of Time, which belongs to pure Sensibility. The succession

of real objects, whose form is precisely Time, we know empirically,

consequently as _actual_. But it is through the Understanding alone,

by means of Causality, that we gain knowledge of the _necessity_ of

a succession of two states: that is, of a change; and even the fact

that we are able to conceive the necessity of a succession at all,

proves already that the causal law is not known to us empirically,

but given us _à priori_. The Principle of Sufficient Reason is the

general expression for the fundamental form of the necessary connection

between all our objects, _i.e._ representations, which lies in the

innermost depths of our cognitive faculty: it is the form common to all

representations, and the only source of the conception of _necessity_,

which contains absolutely nothing else in it and no other import,

than that of the following of the consequence, when its reason has

been established. Now, the reason why this principle determines the

order of succession in Time in the class of representations we are now

investigating, in which it figures as the law of causality, is, that

Time is the form of these representations, therefore the necessary

connection appears here as the rule of succession. In other forms of

the principle of sufficient reason, the necessary connection it always

demands will appear under quite different forms from that of Time,

therefore not as succession; still it always retains the character of

a necessary connection, by which the identity of the principle under

all its forms, or rather the unity of the root of all the laws of which

that principle is the common expression, reveals itself.

[102] Kant, "Kritik d. r. Vern." 1st edition, p. 275; 5th edition,

p. 331. (English translation by M. Müller, p. 236.)

If Kant's assertion were correct, which I dispute, our only way of

knowing the reality of succession would be through its necessity; but

this would presuppose an Understanding that embraced all the series of

causes and effects at once, consequently an omniscient Understanding.

Kant has burdened the Understanding with an impossibility, merely in

order to have less need of Sensibility.

How can we reconcile Kant's assertion that our only means of knowing

the objective reality of succession is by the necessity with which

effect follows cause, with his other assertion[103] that succession

in Time is our only empirical criterion for determining which of two

states is cause, and which effect. Who does not see the most obvious

circle here?

[103] Kant, "Krit. d. r. Vern." vol. i. p. 203 of the 1st edition;

p. 249 of the 5th edition. (English translation by M. Müller, p.

178.)

If we knew objectiveness of succession through Causality, we should

never be able to think it otherwise than as Causality, and then it

would be nothing else than Causality. For, if it were anything else, it

would have other distinctive signs by which to be recognised; now this

is just what Kant denies. Accordingly, if Kant were right, we could

not say: "This state is the effect of that one, wherefore it follows

it;" for following and being an effect, would be one and the same

thing, and this proposition a tautology. Besides, if we do away with

all distinction between following _upon_ and following _from_, we once

more yield the point to Hume, who declared all consequence to be mere

sequence and therefore denied that distinction likewise.

Kant's proof would, consequently, be reduced to this: that,

empirically, we only know _actuality_ of succession; but as besides we

recognise _necessity_ of succession in certain series of occurrences,

and even know before all experience that every possible occurrence must

have a fixed place in some one of these series, the reality and the

_à priority_ of the causal law follow as a matter of course, the only

correct proof of the latter being the one I have given in § 21 of this

work.

Parallel with the Kantian theory: that the causal nexus alone renders

objective succession and our knowledge of it possible, there runs

another: that coexistence and our knowledge of it are only possible

through reciprocity. In the "Critique of Pure Reason" they are

presented under the title: "Third Analogy of Experience." Here Kant

goes so far as to say that "the co-existence of phenomena, which

exercise no reciprocal action on one another, but are separated by

a perfectly empty space, could never become an object of possible

perception"[104] (which, by the way, would be a proof _à priori_ that

there is no empty space between the fixed stars), and that "the light

which _plays between_ our eyes and celestial bodies"--an expression

conveying surreptitiously the thought, that this starlight not only

acts upon our eyes, but is acted upon by them also--"produces an

intercommunity between us and them, and proves the co-existence of the

latter." Now, even empirically, this last assertion is false; since the

sight of a fixed star by no means proves its coexistence simultaneously

with its spectator, but, at most, its existence some years, nay even

some centuries before. Besides, this second Kantian theory stands and

falls with the first, only it is far more easily detected; and the

nullity of the whole conception of reciprocity has been shown in § 20.

[104] Kant, "Krit. d. r. Vern." pp. 212 and 213 of the 1st edition.

(English translation, pp. 185 and 186.)

The arguments I have brought forward against Kant's proof may be

compared with two previous attacks made on it by Feder,[105] and by G.

E. Schulze.[106]

[105] Feder, "Ueber Raum und Causalität." sect. 29.

[106] G. E. Schulze, "Kritik der theoretischen Philosophie," vol.

ii. p. 422 _sqq._

Not without considerable hesitation did I thus venture (in 1813) to

attack a theory which had been universally received as a demonstrated

truth, is repeated even now in the latest publications,[107] and forms

a chief point in the doctrine of one for whose profound wisdom I have

the greatest reverence and admiration; one to whom, indeed, I owe so

much, that his spirit might truly say to me, in the words of Homer:

Ἀχλὺν δ' αὖ τοι ἀπ' ὀφθαλμῶν ἕλον, ἣ πρὶν ἐπῆεν.[108]

[107] For instance, in Fries' "Kritik der Vernunft," vol. ii. p. 85.

[108] I lifted from thine eyes the darkness which covered them

before. (Tr.'s Ad.)

§ 24. _Of the Misapplication of the Law of Causality._

From the foregoing exposition it follows, that the application of the

causal law to anything but _changes_ in the material, empirically given

world, is an abuse of it. For instance, it is a misapplication to make

use of it with reference to physical forces, without which no changes

could take place; or to Matter, _on_ which they take place; or to the

world, to which we must in that case attribute an absolutely objective

existence independently of our intellect; indeed in many other cases

besides. I refer the reader to what I have said on this subject in my

chief work.[109] Such misapplications always arise, partly, through

our taking the conception of cause, like many other metaphysical and

ethical conceptions, in far _too wide_ a sense; partly, through our

forgetting that the causal law is certainly a presupposition which

we bring with us into the world, by which the perception of things

outside us becomes possible; but that, just on that account, we are

not authorized in extending beyond the range and independently of our

cognitive faculty a principle, which has its origin in the equipment of

that faculty, nor in assuming it to hold good as the everlasting order

of the universe and of all that exists.

[109] "Die Welt a. W. u. V." 2nd edition, vol. ii. ch. iv. p. 42

_et seqq._; 3rd edition, vol. ii. p. 46 _et seqq._

§ 25. _The Time in which a Change takes place._

As the Principle of Sufficient Reason of Becoming is exclusively

applicable to _changes_, we must not omit to mention here, that the

ancient philosophers had already raised the question as to the time in

which a change takes place, there being no possibility of it taking

place during the existence of the preceding state nor after the new one

has supervened. Yet, if we assign a special time to it between both

states, a body would, during this time, be neither in the first nor in

the second state: a dying man, for instance, would be neither alive nor

dead; a body neither at rest nor in movement: which would be absurd.

The scruples and sophistic subtleties which this question has evoked,

may be found collected together in Sextus Empiricus "Adv. Mathem."

lib. ix. 267-271, and "Hypat." iii. c. 14; the subject is likewise

dealt with by Gellius, l. vi. c. 13--Plato[110] had disposed somewhat

cavalierly of this knotty point, by maintaining that changes take place

_suddenly_ and occupy _no time at all_; they occur, he says, in the

ἐξαίφνης (_in repentino_), which he calls an ἄτοπος φύσις, ἐν χρόνῳ

οὐδὲν οὖσα; a strange, timeless existence (which nevertheless comes

within Time).

[110] Plato, "Parmenides," p. 138, ed. Bip.

It was accordingly reserved for the perspicacity of Aristotle to clear

up this difficult point, which he has done profoundly and exhaustively

in the sixth Book of Physics, chap. i.-viii. His proof that no change

takes place suddenly (in Plato's ἐξαίφνης), but that each occurs only

gradually and therefore occupies a certain time, is based entirely upon

the pure, _à priori_ intuition of Time and of Space; but it is also

very subtle. The pith of this very lengthy demonstration may, however,

be reduced to the following propositions. When we say of objects that

they limit each other, we mean, that both have their extreme ends in

common; therefore only two extended things can be conterminous, never

two indivisible ones, for then they would be _one_--_i.e._ only lines,

but not mere points, can be conterminous. He then transfers this from

Space to Time. As there always remains a line between two points, so

there always remains a time between two _nows_; this is the time in

which a change takes place--_i.e._ when _one_ state is in the first,

and _another_ in the second, _now_. This time, like every other, is

divisible to infinity; consequently, whatever is changing passes

through an infinite number of degrees within that time, through which

the second state gradually grows out of that _first_ one.--The process

may perhaps be made more intelligible by the following explanation.

Between two consecutive states the difference of which is perceptible

to our senses, there are always several intermediate states, the

difference between which is not perceptible to us; because, in order to

be sensuously perceptible, the newly arising state must have reached a

certain degree of intensity or of magnitude: it is therefore preceded

by degrees of lesser intensity or extension, in passing through which

it gradually arises. Taken collectively, these are comprised under

the name of _change_, and the time occupied by them is called _the

time of change_. Now, if we apply this to a body being propelled, the

first effect is a certain vibration of its inner parts, which, after

communicating the impulse to other parts, breaks out into external

motion.--Aristotle infers quite rightly from the infinite divisibility

of Time, that everything which fills it, therefore every change, _i.e._

every passage from one state to another, must likewise be susceptible

of endless subdivision, so that all that arises, does so in fact by the

concourse of an infinite multitude of parts; accordingly its genesis is

always gradual, never sudden. From these principles and the consequent

gradual arising of each movement, he draws the weighty inference

in the last chapter of this Book, that nothing indivisible, no mere

_point_ can move. And with this conclusion Kant's definition of Matter,

as "that which moves in Space," completely harmonizes.

This law of the continuity and gradual taking place of all changes

which Aristotle was thus the first to lay down and prove, we find

stated three times by Kant: in his "Dissertatio de mundi sensibilis et

intelligibilis forma," § 14, in the "Critique of Pure Reason,"[111] and

finally in his "Metaphysical First Principles of Natural Science."[112]

In all three places his exposition is brief, but also less thorough

than that of Aristotle; still, in the main, both entirely agree. We can

therefore hardly doubt that, directly or indirectly, Kant must have

derived these ideas from Aristotle, though he does not mention him.

Aristotle's proposition--οὐκ ἔστι ἀλλήλων ἐχόμενα τὰ νῦν ("the moments

of the present are not continuous")--we here find expressed as follows:

"between two moments there is always a time," to which may be objected

that "even between two centuries there is none; because in Time as

in Space, there must always be a pure limit."--Thus Kant, instead of

mentioning Aristotle, endeavours in the first and earliest of his

three statements to identify the theory he is advancing with Leibnitz'

_lex continuitatis_. If they really were the same, Leibnitz must have

derived his from Aristotle. Now Leibnitz[113] first stated this _Loi

de la continuité_ in a letter to Bayle.[114] There, however, he calls

it _Principe de l'ordre général_, and gives under this name a very

general, vague, chiefly geometrical argumentation, having no direct

bearing on the time of change, which he does not even mention.

[111] Kant, "Krit. d. r. Vern." 1st edition, p. 207; 5th edition,

p. 253. (English translation by M. Müller, p. 182.)

[112] Kant, "Metaphysische Anfangsgründe der Naturwissenschaft."

End of the "Allgemeine Anmerkung zur Mechanik."

[113] According to his own assertion, p. 189 of the "Opera philos."

ed. Erdmann.

[114] _Ibid._ p. 104.