OF METHODS OF ACQUIRING CLEAR SCIENTIFIC IDEAS; _and first_ OF
INTELLECTUAL EDUCATION.
APHORISM XXIX.
_The Methods by which the acquisition of clear Scientific Ideas is
promoted, are mainly two_; Intellectual Education _and_ Discussion
of Ideas.
APHORISM XXX.
_The Idea of Space becomes more clear by studying_ Geometry; _the
Idea of Force, by studying_ Mechanics; _the Ideas of Likeness,
of Kind, of Subordination of Classes, by studying_ Natural History.
APHORISM XXXI.
Elementary Mechanics _should now form a part of intellectual
education, in order that the student may understand the Theory of
Universal Gravitation: for an intellectual education should
cultivate such ideas as enable the student to understand the most
complete and admirable portions of the knowledge which the human
race has attained to._
APHORISM XXXII.
Natural History _ought to form a part of intellectual education, in
order to correct certain prejudices which arise from cultivating the
intellect by means of mathematics alone; and in order to lead the
student to see that the division of things into Kinds, and the
attribution and use of Names, are processes susceptible of great
precision._ {165}
THE ways in which men become masters of those clear and yet
comprehensive conceptions which the formation and reception of
science require, are mainly two; which, although we cannot reduce
them to any exact scheme, we may still, in a loose use of the term,
call _Methods_ of acquiring clear Ideas. These two ways are
Education and Discussion.
1. (I.) _Idea of Space._--It is easily seen that Education may do at
least something to render our ideas distinct and precise. To learn
Geometry in youth, tends, manifestly, to render our idea of space
clear and exact. By such an education, all the relations, and all
the consequences of this idea, come to be readily and steadily
apprehended; and thus it becomes easy for us to understand portions
of science which otherwise we should by no means be able to
comprehend. The conception of _similar triangles_ was to be
mastered, before the disciples of Thales could see the validity of
his method of determining the height of lofty objects by the length
of their shadows. The conception of _the sphere with its circles_
had to become familiar, before the annual motion of the sun and its
influence upon the lengths of days could be rightly traced. The
properties of circles, combined with the _pure_[13\3] _doctrine of
motion_, were required as an introduction to the theory of
Epicycles: the properties of _conic sections_ were needed, as a
preparation for the discoveries of Kepler. And not only was it
necessary that men should possess a _knowledge_ of certain figures
and their properties; but it was equally necessary that they should
have the _habit of reasoning_ with perfect steadiness, precision,
and conclusiveness concerning the relations of space. No small
discipline of the mind is requisite, in most cases, to accustom it
to go, with complete insight and security, through the
demonstrations respecting intersecting planes and lines, dihedral
and trihedral angles, which occur in solid geometry. Yet how
absolutely necessary is a perfect mastery of such reasonings, to him
who is to explain the motions of the moon in {166} latitude and
longitude! How necessary, again, is the same faculty to the student
of crystallography! Without mathematical habits of conception and of
thinking, these portions of science are perfectly inaccessible. But
the early study of plane and solid geometry gives to all tolerably
gifted persons, the habits which are thus needed. The discipline of
following the reasonings of didactic works on this subject, till we
are quite familiar with them, and of devising for ourselves
reasonings of the same kind, (as, for instance, the solutions of
problems proposed,) soon gives the mind the power of _discoursing_
with perfect facility concerning the most complex and multiplied
relations of space, and enables us to refer to the properties of all
plane and solid figures as surely as to the visible forms of
objects. Thus we have here a signal instance of the efficacy of
education in giving to our Conceptions that clearness, which the
formation and existence of science indispensably require.
[Note 13\3: See _Hist. Sc. Ideas_, b. ii. c. xiii.]
2. It is not my intention here to enter into the details of the form
which should be given to education, in order that it may answer the
purposes now contemplated. But I may make a remark, which the above
examples naturally suggest, that in a mathematical education,
considered as a preparation for furthering or understanding physical
science, Geometry is to be cultivated, far rather than Algebra:--the
properties of space are to be studied and reasoned upon as they are
in themselves, not as they are replaced and disguised by symbolical
representations. It is true, that when the student is become quite
familiar with elementary geometry, he may often enable himself to
deal in a more rapid and comprehensive manner with the relations of
space, by using the language of symbols and the principles of
symbolical calculation: but this is an ulterior step, which may be
added to, but can never be substituted for, the direct cultivation
of geometry. The method of symbolical reasoning employed upon
subjects of geometry and mechanics, has certainly achieved some
remarkable triumphs in the treatment of the theory of the universe.
These successful {167} applications of symbols in the highest
problems of physical astronomy appear to have made some teachers of
mathematics imagine that it is best to _begin_ the pupil's course
with such symbolical generalities. But this mode of proceeding will
be so far from giving the student clear ideas of mathematical
relations, that it will involve him in utter confusion, and probably
prevent his ever obtaining a firm footing in geometry. To commence
mathematics in such a way, would be much as if we should begin the
study of a language by reading the highest strains of its lyrical
poetry.
3. (II.) _Idea of Number, &c._--The study of mathematics, as I need
hardly observe, developes and renders exact, our conceptions of the
relations of number, as well as of space. And although, as we have
already noticed, even in their original form the conceptions of
number are for the most part very distinct, they may be still
further improved by such discipline. In complex cases, a methodical
cultivation of the mind in such subjects is needed: for instance,
questions concerning Cycles, and Intercalations, and Epacts, and the
like, require very great steadiness of arithmetical apprehension in
order that the reasoner may deal with them rightly. In the same
manner, a mastery of problems belonging to the science of Pure
Motion, or, as I have termed it, _Mechanism_, requires either great
natural aptitude in the student, or a mind properly disciplined by
suitable branches of mathematical study.
4. Arithmetic and Geometry have long been standard portions of the
education of cultured persons throughout the civilized world; and
hence all such persons have been able to accept and comprehend those
portions of science which depend upon the idea of space: for
instance, the doctrine of the globular form of the earth, with its
consequences, such as the measures of latitude and longitude;--the
heliocentric system of the universe in modern, or the geocentric in
ancient times;--the explanation of the rainbow; and the like. In
nations where there is no such education, these portions of science
cannot exist as a part of the general stock of the knowledge of
society, however intelligently they {168} may be pursued by single
philosophers dispersed here and there in the community.
5. (III.) _Idea of Force._--As the idea of Space is brought out in
its full evidence by the study of Geometry, so the idea of Force is
called up and developed by the study of the science of Mechanics. It
has already been shown, in our scrutiny of the Ideas of the
Mechanical Sciences, that Force, the Cause of motion or of
equilibrium, involves an independent Fundamental Idea, and is quite
incapable of being resolved into any mere modification of our
conceptions of space, time, and motion. And in order that the
student may possess this idea in a precise and manifest shape, he
must pursue the science of Mechanics in the mode which this view of
its nature demands;--that is, he must study it as an independent
science, resting on solid elementary principles of its own, and not
built upon some other unmechanical science as its substructure. He
must trace the truths of Mechanics from their own axioms and
definitions; these axioms and definitions being considered as merely
means of bringing into play the Idea on which the science depends.
The conceptions of force and matter, of action and reaction, of
momentum and inertia, with the reasonings in which they are
involved, cannot be evaded by any substitution of lines or symbols
for the conceptions. Any attempts at such substitution would render
the study of Mechanics useless as a preparation of the mind for
physical science; and would, indeed, except counteracted by great
natural clearness of thought on such subjects, fill the mind with
confused and vague notions, quite unavailing for any purposes of
sound reasoning. But, on the other hand, the study of Mechanics, in
its genuine form, as a branch of education, is fitted to give a most
useful and valuable precision of thought on such subjects; and is
the more to be recommended, since, in the general habits of most
men's minds, the mechanical conceptions are tainted with far greater
obscurity and perplexity than belongs to the conceptions of number,
space, and motion.
6. As habitually distinct conceptions of _space_ and {169} _motion_
were requisite for the reception of the doctrines of formal
astronomy, (the Ptolemaic and Copernican system,) so a clear and
steady conception of _force_ is indispensably necessary for
understanding the Newtonian system of physical astronomy. It may be
objected that the study of Mechanics as a science has not commonly
formed part of a liberal education in Europe, and yet that educated
persons have commonly accepted the Newtonian system. But to this we
reply, that although most persons of good intellectual culture have
professed to assent to the Newtonian system of the universe, yet
they have, in fact, entertained it in so vague and perplexed a
manner as to show very clearly that a better mental preparation than
the usual one is necessary, in order that such persons may really
understand the doctrine of universal attraction. I have elsewhere
spoken of the prevalent indistinctness of mechanical
conceptions[14\3]; and need not here dwell upon the indications,
constantly occurring in conversation and in literature, of the utter
inaccuracy of thought on such subjects which may often be detected;
for instance, in the mode in which many men speak of centrifugal and
centripetal forces;--of projectile and central forces;--of the
effect of the moon upon the waters of the ocean; and the like. The
incoherence of ideas which we frequently witness on such points,
shows us clearly that, in the minds of a great number of men, well
educated according to the present standard, the acceptance of the
doctrine of Universal Gravitation is a result of traditional
prejudice, not of rational conviction. And those who are Newtonians
on such grounds, are not at all more intellectually advanced by
being Newtonians in the nineteenth century, than they would have
been by being Ptolemaics in the fifteenth.
[Note 14\3: _Hist. Sc. Ideas_, b. iii. c. x.]
7. It is undoubtedly in the highest degree desirable that all great
advances in science should become the common property of all
cultivated men. And this can only be done by introducing into the
course of a liberal education such studies as unfold and fix in
men's minds {170} the fundamental ideas upon which the
new-discovered truths rest. The progress made by the ancients in
geography, astronomy, and other sciences, led them to assign, wisely
and well, a place to arithmetic and geometry among the steps of an
ingenuous education. The discoveries of modern times have rendered
these steps still more indispensable; for we cannot consider a man
as cultivated up to the standard of his times, if he is not only
ignorant of, but incapable of comprehending, the greatest
achievements of the human intellect. And as innumerable discoveries
of all ages have thus secured to Geometry her place as a part of
good education, so the great discoveries of Newton make it proper to
introduce Elementary Mechanics as a part of the same course. If the
education deserve to be called _good_, the pupil will not remain
ignorant of those discoveries, the most remarkable extensions of the
field of human knowledge which have ever occurred. Yet he cannot by
possibility comprehend them, except his mind be previously
disciplined by mechanical studies. The period appears now to be
arrived when we may venture, or rather when we are bound to
endeavour, to include a new class of Fundamental Ideas in the
elementary discipline of the human intellect. This is indispensable,
if we wish to educe the powers which we know that it possesses, and
to enrich it with the wealth which lies within its reach[15\3].
[Note 15\3: The University of Cambridge has, by a recent law, made
an examination in Elementary Mechanics requisite for the Degree of
B.A.]
8. By the view which is thus presented to us of the nature and
objects of intellectual education, we are led to consider the mind
of man as undergoing a progress from age to age. By the discoveries
which are made, and by the clearness and evidence which, after a
time, (not suddenly nor soon,) the truths thus discovered acquire,
one portion of knowledge after another becomes _elementary_; and if
we would really secure this progress, and make men share in it,
these new portions must be treated as elementary in the constitution
of a {171} liberal education. Even in the rudest forms of
intelligence, man is immeasurably elevated above the unprogressive
brute, for the idea of number is so far developed that he can count
his flock or his arrows. But when number is contemplated in a
speculative form, he has made a vast additional progress; when he
steadily apprehends the relations of space, he has again advanced;
when in thought he carries these relations into the vault of the
sky, into the expanse of the universe, he reaches a higher
intellectual position. And when he carries into these wide regions,
not only the relations of space and time, but of cause and effect,
of force and reaction, he has again made an intellectual advance;
which, wide as it is at first, is accessible to all; and with which
all should acquaint themselves, if they really desire to prosecute
with energy the ascending path of truth and knowledge which lies
before them. This should be an object of exertion to all ingenuous
and hopeful minds. For, that exertion is necessary,--that after all
possible facilities have been afforded, it is still a matter of toil
and struggle to appropriate to ourselves the acquisitions of great
discoverers, is not to be denied. Elementary mechanics, like
elementary geometry, is a study accessible to all: but like that
too, or perhaps more than that, it is a study which requires effort
and contention of mind,--a forced steadiness of thought. It is long
since one complained of this labour in geometry; and was answered
that in that region there is no _Royal Road_. The same is true of
Mechanics, and must be true of all branches of solid education. But
we should express the truth more appropriately in our days by saying
that there is no _Popular Road_ to these sciences. In the mind, as
in the body, strenuous exercise alone can give strength and
activity. The art of exact thought can be acquired only by the
labour of close thinking.
9. (IV.) _Chemical Ideas._--We appear then to have arrived at a
point of human progress in which a liberal education of the
scientific intellect should include, besides arithmetic, elementary
geometry and mechanics. {172} The question then occurs to us,
whether there are any other Fundamental Ideas, among those belonging
to other sciences, which ought also to be made part of such an
education;--whether, for example, we should strive to develope in
the minds of all cultured men the ideas of _polarity_, mechanical
and chemical, of which we spoke in a former part of this work.
The views to which we have been conducted by the previous inquiry
lead us to reply that it would not be well at present to make
_chemical_ Polarities, at any rate, a subject of elementary
instruction. For even the most profound and acute philosophers who
have speculated upon this subject,--they who are leading the van in
the march of discovery,--do not seem yet to have reduced their
thoughts on this subject to a consistency, or to have taken hold of
this idea of Polarity in a manner quite satisfactory to their own
minds. This part of the subject is, therefore, by no means ready to
be introduced into a course of general elementary education; for,
with a view to such a purpose, nothing less than the most thoroughly
luminous and transparent condition of the idea will suffice. Its
whole efficacy, as a means and object of disciplinal study, depends
upon there being no obscurity, perplexity, or indefiniteness with
regard to it, beyond that transient deficiency which at first exists
in the learner's mind, and is to be removed by his studies. The idea
of chemical Polarity is not yet in this condition; and therefore is
not yet fit for a place in education. Yet since this idea of
Polarity is the most general idea which enters into chemistry, and
appears to be that which includes almost all the others, it would be
unphilosophical, and inconsistent with all sound views of science,
to introduce into education some chemical conceptions, and to omit
those which depend upon this idea: indeed such a partial adoption of
the science could hardly take place without not only omitting, but
misrepresenting, a great part of our chemical knowledge. The
conclusion to which we are necessarily led, therefore, is
this:--that at present chemistry {173} cannot with any advantage,
form a portion of the general intellectual education[16\3].
[Note 16\3: I do not here stop to prove that an education (if it be
so called) in which the memory only retains the verbal expression of
results, while the mind does not apprehend the principles of the
subject, and therefore cannot even understand the words in which its
doctrines are expressed, is of no value whatever to the intellect,
but rather, is highly hurtful to the habits of thinking and
reasoning.]
10. (V.) _Natural-History Ideas._--But there remains still another
class of Ideas, with regard to which we may very properly ask
whether they may not advantageously form a portion of a liberal
education: I mean the Ideas of definite Resemblance and Difference,
and of one set of resemblances subordinate to another, which form
the bases of the classificatory sciences. These Ideas are developed
by the study of the various branches of Natural History, as Botany,
and Zoology; and beyond all doubt, those pursuits, if assiduously
followed, very materially affect the mental habits. There is this
obvious advantage to be looked for from the study of Natural
History, considered as a means of intellectual discipline:--that it
gives us, in a precise and scientific form, examples of the classing
and naming of objects; which operations the use of common language
leads us constantly to perform in a loose and inexact way. In the
usual habits of our minds and tongues, things are distinguished or
brought together, and names are applied, in a manner very
indefinite, vacillating, and seemingly capricious: and we may
naturally be led to doubt whether such defects can be
avoided;--whether exact distinctions of things, and rigorous use of
words be possible. Now upon this point we may receive the
instruction of Natural History; which proves to us, by the actual
performance of the task, that a precise classification and
nomenclature are attainable, at least for a mass of objects all of
the same kind. Further, we also learn from this study, that there
may exist, not only an exact distinction of kinds of things, but a
series of distinctions, one set subordinate to another, and the more
general including {174} the more special, so as to form a system of
classification. All these are valuable lessons. If by the study of
Natural History we evolve, in a clear and well defined form, the
conceptions of _genus_, _species_, and of _higher_ and _lower steps_
of classification, we communicate precision, clearness, and method
to the intellect, through a great range of its operations.
11. It must be observed, that in order to attain the disciplinal
benefit which the study of Natural History is fitted to bestow, we
must teach the _natural_ not the artificial _classifications_; or at
least the natural as well as the artificial. For it is important for
the student to perceive that there are classifications, not merely
arbitrary, founded upon some _assumed_ character, but natural,
recognized by some _discovered_ character: he ought to see that our
classes being collected according to one mark, are confirmed by many
marks not originally stated in our scheme; and are thus found to be
grouped together, not by a single resemblance, but by a mass of
resemblances, indicating a natural affinity. That objects may be
collected into such groups, is a highly important lesson, which
Natural History alone, pursued as the science of _natural classes_,
can teach.
12. Natural History has not unfrequently been made a portion of
education: and has in some degree produced such effects as we have
pointed out. It would appear, however, that its lessons have, for
the most part, been very imperfectly learnt or understood by persons
of ordinary education: and that there are perverse intellectual
habits very commonly prevalent in the cultivated classes, which
ought ere now to have been corrected by the general teaching of
Natural History. We may detect among speculative men many prejudices
respecting the nature and rules of reasoning, which arise from pure
mathematics having been so long and so universally the instrument of
intellectual cultivation. Pure Mathematics reasons from definitions:
whatever term is introduced into her pages, as a _circle_, or a
_square_, its definition comes along with it: and this definition is
supposed to supply all that the reasoner needs to know, respecting
the term. {175} If there be any doubt concerning the validity of the
conclusion, the doubt is resolved by recurring to the definitions.
Hence it has come to pass that in other subjects also, men seek for
and demand definitions as the most secure foundation of reasoning.
The definition and the term defined are conceived to be so far
identical, that in all cases the one may be substituted for the
other; and such a substitution is held to be the best mode of
detecting fallacies.
13. It has already been shown that even geometry is not founded upon
definitions alone: and we shall not here again analyse the fallacy
of this belief in the supreme value of definitions. But we may
remark that the study of Natural History appears to be the proper
remedy for this erroneous habit of thought. For in every department
of Natural History the object of our study is _kinds_ of things, not
one of which kinds can be rigorously defined, yet all of them are
sufficiently definite. In these cases we may indeed give a specific
description of one of the kinds, and may call it a definition; but
it is clear that such a definition does not contain the essence of
the thing. We say[17\3] that the Rose Tribe are 'Polypetalous
dicotyledons, with lateral styles, superior simple ovaria, regular
perigynous stamens, exalbuminous definite seeds, and alternate
stipulate leaves.' But no one would say that this was our essential
conception of a rose, to be substituted for it in all cases of doubt
or obscurity, by way of making our reasonings perfectly clear. Not
only so; but as we have already seen[18\3], the definition does not
even apply to all the tribe. For the stipulæ are absent in Lowea:
the albumen is present in Neillia: the fruit of Spiræa sorbifolia is
capsular. If, then, we can possess any certain knowledge in Natural
History, (which no cultivator of the subject will doubt,) it is
evident that our knowledge cannot depend on the possibility of
laying down exact definitions and reasoning from them.
[Note 17\3: Lindley's _Nat. Syst. Bot._ p. 81.]
[Note 18\3: _Hist. Sc. Ideas,_ b. viii. c. ii. sect. 3.]
14. But it may be asked, if we cannot define a {176} word, or a
class of things which a word denotes, how can we distinguish what it
does mean from what it does not mean? How can we say that it
signifies one thing rather than another, except we declare what is
its signification?
The answer to this question involves the general principle of a
natural method of classification, which has already been
stated[19\3] and need not here be again dwelt on. It has been shown
that names of _kinds_ of things (_genera_) associate them according
to total resemblances, not partial characters. The principle which
connects a group of objects in natural history is not a
_definition_, but a _type_. Thus we take as the type of the Rose
family, it may be, the common _wild rose_; all species which
resemble this flower more than they resemble any other group of
species are also _roses_, and form one _genus_. All genera which
resemble Roses more than they resemble any other group of genera are
of the same _family_. And thus the Rose family is collected about
some one species, which is the type or central point of the group.
[Note 19\3: _Hist. Sc. Ideas,_ b. viii. c. ii. sect. 3.]
In such an arrangement, it may readily be conceived that though the
nucleus of each group may cohere firmly together, the outskirts of
contiguous groups may approach, and may even be intermingled, so
that some species may doubtfully adhere to one group or another. Yet
this uncertainty does not at all affect the truths which we find
ourselves enabled to assert with regard to the general mass of each
group. And thus we are taught that there may be very important
differences between two groups of objects, although we are unable to
tell where the one group ends and where the other begins; and that
there may be propositions of indisputable truth, in which it is
impossible to give unexceptionable definitions of the terms
employed.
15. These lessons are of the highest value with regard to all
employments of the human mind; for the mode in which words in common
use acquire their meaning, approaches far more nearly to the _Method
of_ {177} _Type_ than to the method of definition. The terms which
belong to our practical concerns, or to our spontaneous and
unscientific speculations, are rarely capable of exact definition.
They have been devised in order to express assertions, often very
important, yet very vaguely conceived: and the signification of the
word is extended, as far as the assertion conveyed by it can be
extended, by apparent connexion or by analogy. And thus, in all the
attempts of man to grasp at knowledge, we have an exemplification of
that which we have stated as the rule of induction, that Definition
and Proposition are mutually dependent, each adjusted so as to give
value and meaning to the other: and this is so, even when both the
elements of truth are defective in precision: the Definition being
replaced by an incomplete description or a loose reference to a
Type; and the Proposition being in a corresponding degree insecure.
16. Thus the study of Natural History, as a corrective of the belief
that definitions are essential to substantial truth, might be of
great use; and the advantage which might thus be obtained is such as
well entitles this study to a place in a liberal education. We may
further observe, that in order that Natural History may produce such
an effect, it must be studied by inspection of the _objects_
themselves, and not by the reading of books only. Its lesson is,
that we must in all cases of doubt or obscurity refer, not to words
or definitions, but to things. The Book of Nature is its dictionary:
it is there that the natural historian looks, to find the meaning of
the words which he uses[20\3]. So {178} long as a plant, in its most
essential parts, is more _like_ a rose than any thing else, it _is_
a rose. He knows no other definition.
[Note 20\3: It is a curious example of the influence of the belief
in definitions, that elementary books have been written in which
Natural History is taught in the way of question and answer, and
consequently by means of words alone. In such a scheme, of course
all objects are _defined_: and we may easily anticipate the value of
the knowledge thus conveyed. Thus, 'Iron is a well-known hard metal,
of a darkish gray colour, and very elastic:' 'Copper is an
orange-coloured metal, more sonorous than any other, and the most
elastic of any except iron.' This is to pervert the meaning of
education, and to make it a business of mere words.]
17. (VI.) _Well-established Ideas alone to be used._--We may assert
in general what we have elsewhere, as above, stated specially with
reference to the fundamental principles of chemistry:--no Ideas are
suited to become the elements of elementary education, till they
have not only become perfectly distinct and fixed in the minds of
the leading cultivators of the science to which they belong; but
till they have been so for some considerable period. The entire
clearness and steadiness of view which is essential to sound
science, must have time to extend itself to a wide circle of
disciples. The views and principles which are detected by the most
profound and acute philosophers, are soon appropriated by all the
most intelligent and active minds of their own and of the following
generations; and when this has taken place, (and not till then,) it
is right, by a proper constitution of our liberal education, to
extend a general knowledge of such principles to all cultivated
persons. And it follows, from this view of the matter, that we are
by no means to be in haste to adopt, into our course of education,
all new discoveries as soon as they are made. They require some
time, in order to settle into their proper place and position in
men's minds, and to show themselves under their true aspects; and
till this is done, we confuse and disturb, rather than enlighten and
unfold, the ideas of learners, by introducing the discoveries into
our elementary instruction. Hence it was perhaps reasonable that a
century should elapse from the time of Galileo, before the rigorous
teaching of Mechanics became a general element of intellectual
training; and the doctrine of Universal Gravitation was hardly ripe
for such an employment till the end of the last century. We must not
direct the unformed youthful mind to launch its little bark upon the
waters of speculation, till all the agitation of discovery, with its
consequent fluctuation and controversy, has well subsided.
18. But it may be asked, How is it that time {179} operates to give
distinctness and evidence to scientific ideas? In what way does it
happen that views and principles, obscure and wavering at first,
after a while become luminous and steady? Can we point out any
process, any intermediate steps, by which this result is produced?
If we can, this process must be an important portion of the subject
now under our consideration.
To this we reply, that the transition from the hesitation and
contradiction with which true ideas are first received, to the
general assent and clear apprehension which they afterwards obtain,
takes place through the circulation of various arguments for and
against them, and various modes of presenting and testing them, all
which we may include under the term _Discussion_, which we have
already mentioned as the second of the two ways by which scientific
views are developed into full maturity.
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