The evolution of general ideas

Having thus acquainted ourselves with this new factor—speech—which as an instrument of abstraction becomes steadily more and more important, we can take up our subject from the point at which we left it. In passing from the absence to the presence of the word, from the lower to the intermediate forms of abstraction, we must again insist on our principal aim: viz., to prove that abstraction and generalisation are functions of the completely evolved mind. They exist in embryo in perception, and in the image, and at their extreme limit involve suppression of all concrete representation. This conclusion will hardly be contradicted. The difficulty is to follow the evolution step by step, stage after stage, and to note the difference by objective marks.

For intermediate abstraction, this operation is very simple. It implies the use of words; it has passed the level of pre-linguistic abstraction and generalisation. We may go farther, and—always with the aid of words—establish two classes within the total category of mean abstraction:

1. The lower forms, bordering on generic images, whose objective mark is the feeble participation of the word: it can indeed be altogether foregone, and is only in the least degree an instrument of substitution.

2. The higher forms, approximating to the class of pure concepts, and having as their objective mark the fact that words are indispensable, since these have now become an instrument of substitution, though still accompanied by some sensory representation.

The legitimacy of this division can be justified only by a detailed comparison of the two classes.

I.

Before giving examples that determine the nature and intellectual trend of the lower forms, a theoretical question presents itself which cannot be eluded, albeit any profound discussion of it belongs to the theory of cognition rather than to psychology. It is as follows: Is the difference between generic images and the lowest concepts, one of nature or of degree? This question has sometimes been propounded in a less general and more concrete form; Is there any radical difference, any impassable gulf between animal intelligence[67] in its higher, and human intelligence in its lower aspects? Some authors give an absolute negation, others admit community of nature, and of transitional forms.

I shall first reject as inadmissible the argument that identifies abstraction with the use of words. Taine seems at times to admit this: “We think,” he says, “the abstract characters of things by means of the abstract names that are our abstract ideas, and the formation of our ideas is no more than the formation of names which are substitutes.”[68] Clearly if abstraction is impossible without words, this operation could only begin with speech. All that was said above (Chap. I) proves the inanity of such an assertion.

Let us, in order to discuss the question profitably, sum up the principal characteristics of generic images on the one hand, of inferior concepts on the other.

Generic images are: (1) simple and of the practical order; (2) the result of often-repeated experiences; (3) extracts from very salient resemblances; (4) a condensation into a visual, auditory, tactile, or olfactory representation. They are the fruit of passive assimilation.

The inferior concepts most akin to them, which we are studying in the present instance, are in character: (1) less simple; (2) less frequently repeated in experience; (3) they assume as material, similarities mingled with sufficiently numerous differences; (4) they are fixed by a word. They are the fruit of active assimilation.

It may be said that the two classes, when thus opposed to each other, present but minimal differences, save for the addition of words. For the moment, indeed, the word is only an instrument handled by a bad workman, who ignores its efficacy and highest significance, as will be proved below. But were it otherwise, and were the delimitation between the two classes in no way fluctuating, the thesis of a progressive evolution must needs be given up, unless it be admitted to begin only with the appearance of speech.[69]

Romanes describes the passage from the generic image to the concept as follows:

“Water-fowl adopt a somewhat different mode of alighting upon land, or even upon ice, from that which they adopt when alighting upon water; and those kinds which dive from a height (such as terns and gannets) never do so upon land or ice. These facts prove that these animals have one recept answering to a solid substance, and another answering to a fluid. Similarly a man will not dive from a height over hard ground, or over ice, nor will he jump into water in the same way as he jumps upon land. In other words, like the water-fowl, he has two distinct recepts, one of which answers to solid ground, and the other to an unresisting fluid. But unlike the water-fowl, he is able to bestow upon each of these recepts a name, and thus to raise them both to the level of concepts. So far as the practical purposes of locomotion are concerned, it is, of course, immaterial whether or not he thus raises his recepts into concepts; but, as we have seen, for many other purposes it is of the highest importance that he is able to do this. Now, in order to do it, he must be able to set his recept before his own mind as an object of his own thought: before he can bestow upon these generic ideas the names of “solid” and “fluid,” he must have cognised them as ideas. Prior to this act of cognition, these ideas differed in no respect from the recepts of a water-fowl; neither for the requirements of his locomotion is it needful that they should: therefore, in so far as these requirements are concerned, the man makes no call upon his higher faculties of ideation. But, in virtue of this act of cognition whereby he assigns a name to an idea known as such, he has created for himself—and for purposes other than locomotion—a priceless possession; he has formed a concept.”[70]

In point of fact, the transition is not so simple. Romanes omits the intermediate stages: for with fluid and liquid we penetrate into a more elevated order of concepts than those immediately bordering on the generic image. What he well brings out is that the bare introduction of words does not explain everything. It must not be forgotten that if the higher development of the intelligence depends upon the higher development of abstraction, which itself depends upon the development of speech, this last is conditioned, not simply by the faculty of articulation, which exists among many animals, but by anterior cerebral conditions that have to be sought out.

For these, we must return to the distinction loosely established above, between passive and active assimilation. We know that the fundamental mechanism of cognition may be reduced to two antagonistic processes, association and dissociation, assimilation and dissimilation; to combine, to separate; in brief, analysis and synthesis.[71] In the formation of the generic image, as we have seen, assimilation plays the principal part; the mind works only upon similarities. In proportion as we recede from this point, we have the contrary; the mind works more and more upon differences; the primitive and essential operation is a dissociation; the fusion of similarities only appears later. The further back we go, the more analysis preponderates, because we are pursuing resemblances more and more hidden by differences. Coarser minds do not rise above palpable similarities. The peasant who hears a dialect or patois closely akin to his own understands nothing of it; it is another language to him; whereas even a mediocre linguist immediately perceives the identity of words that differ only in accent.

We may represent the differences between generic images, and these general notions that most nearly approximate to them, by the following symbol:

where each line corresponds to an object, and each letter to one of the principal characters of the object. Table I is that of the generic image. A part, A B C, is constantly repeated in each experience; moreover, it is in relief, as indicated by the capitals; the elimination of differences is almost passive,—self-caused; they are forgotten.

Table II is that of a fairly simple general notion. Here A has to be disengaged from all the objects in which it is included. It still has a salient character, indicated by capitals, and recurring in each object; but as it is merged in the differences, as it represents but a poor fraction of the total event, it is not disengaged spontaneously; it exacts a preliminary labor of dissociation and elimination.

Thus understood, the difference between the two processes consists only in the faculty of greater or less dissociation, and we are in no way authorised in assuming a difference of nature.

But the question may be propounded in a different manner,—more precise and more embarrassing. I formulate it thus: the generic image is never, the concept is always a judgment. We know that for logicians (formerly at any rate) the concept is the simple and primitive element; next comes the judgment, uniting two or several concepts; then ratiocination, combining two or several judgments. For the psychologist, on the contrary, affirmation is the fundamental act; the concept is the result of judgments (explicit or implicit), of similarities with exclusion of differences. If in addition to this we recall what was said above: that speech commences with phrases only, that in its simplest form it is the word-phrase; then the debated question may be thus transformed: Is there, between the generic image and judgment in its lower forms, a break in continuity, or a passage by slow transformation?

For the partisans of the first theory, the appearance of judgment is a “passage of the Rubicon” (Max Müller). It is as impossible to deny this as to affirm it positively and indisputably. Romanes, who makes a stand against the “passage of the Rubicon,” admits the following stages in the development of signs, taken as indicative of the development of intelligence itself.

1. The indicative sign; gesture or pronominal root; a dog barking for a door to be opened, etc.

2. The denotative sign which is affixed to particular objects, qualities, or actions; for example, the parrot which on seeing a person utters the name of the person, or some word which it has associated with him, and which for the animal has become the distinctive mark of the person.

3. The connotative or attributive sign, which, rightly or wrongly, is attributed to an entire class of objects having a common quality; for instance, the child which applies the word star to everything that shines.

4. The denominative sign; or the intentional employment of the sign as such, with a full appreciation of its value; for example, the word star in its meaning to the astronomer.

5. The predicative sign, or a proposition formed by the apposition of two denominative signs.[72]

This hierarchical order, while in some measure open to criticism, indicates at least schematically the progressive passage from the concrete to the higher abstractions, and may therefore be accepted.

It is clear that the two first stages scarcely pass beyond the concrete.

To the third, Romanes attaches capital importance: judgment begins with it. It may, however, be asked if affirmation really exists at this stage. For my own part I am inclined to admit it as included in the generic image in its highest degree (for here too there are degrees), under the form not of a proposition, but of an action. The hunting dog assuredly possesses generic images of man and of different kinds of game, under the visual and more especially the olfactory form. When it starts off on the scent of its master, of a hare, or of a partridge, this is surely a judgment of a certain kind, an affirmation, the least doubtful of all, seeing that it is an act. The absence of verbal expression and of logical information in no way alters the fundamental nature of the mental state. We have already (Chap. I.) spoken of practical judgments and ratiocinations; it is needless to reiterate.

The transition from the third to the fourth stage is even more important. It is here that the true concept appears; this point attained, an almost unlimited progress is possible. Now the true cause of the true concept is reflexion. This formula appears to us the simplest, the briefest, the most clear, and the most exact. There is the possibility of concepts where there is the possibility in the mind of detaching a single character (or several), extracted from among many others, of setting it up as an independent entity, of raising it into a known object, i. e., determined in its relations with ourselves, and with other things. Example: to form the general idea of a vertebrate. But this fundamental act—reflexion—is not without antecedents, it does not spring forth as a new apparition. It is the highest degree of attention, i. e., of a mental attitude that we encounter very low down in the animal scale.

Discontinuity of evolution, in the passage from lower to higher, is thus far from being established. Doubtless this, like all other questions of genesis, leaves much to hypothesis, and can only be decided on probabilities: yet these do not appear to favor a rupture in continuity, and opposition of nature.

In sum—to confine ourselves to what is least contestable: given the cerebral and psychological conditions for speech (not for articulate language alone), and application of words to qualities and attributes raised little by little into independent entities,—and the decisive step has been taken. Such is intellectual progress, and we may remark in passing that the process which creates the true concept, leads fatally by the same issue to faith in idols, in the entities realised.

Without for the moment pausing at this last point, let us under a more positive form, and strictly on the lines of experimental psychology, examine the nature of the lower forms of intermediate abstraction, determining it by examples. At the same time we shall fix the intellectual level that corresponds to the moment of transition between generic images (animal form), and the higher abstracts which have still to be studied in detail. The best method is to take as a type such human races as have remained in the savage or half-civilised state: these are more instructive than childhood, because they represent fixed and permanent conditions. We can draw on two principal sources: their languages, and their systems of numeration. Their religious beliefs might also be studied, with the same results, but this would take too long, and would moreover be less definite.[73]

1. The languages, considered under their most general characteristics, reveal a notable impotence for transcending the simplest resemblances, an incurable incapacity for extended generalisations; they hardly rise above the concrete. Words play a very indistinct part; they are the most incomplete substitute—hardly more than a mark, a sign, like gestures—differing from the latter only in the future they carry within them. The study of the ascending progress of generalisation is in effect the study of the successive phases of the emancipation of speech up to the time when it becomes preponderant and dominating. At the actual stage, which might be termed concrete-abstract, it is not yet emancipated; it is a minor, under tutelage.

Let us take in turn substantives, adjectives, and verbs.

The indigenes of Hawaii, says Max Müller (Lectures on the Science of Language, Second Series, II., p. 19), have but one word, “aloba,” to express love, friendship, esteem, gratitude, benevolence, etc.; on the other hand, words to express variations in the direction of the force of the wind are very numerous, proving once more how at its origin abstraction or dissociation is governed by practical causes. In savage languages there are terms to express not merely each species of dog, but their age, the color of their hair, good or bad qualities, etc. So, too, for the horse; there are special words to designate its varieties, and all its movements; to indicate if it is mounted, not mounted, frightened, running away, and the like. The North American Indians have special words for the black oak, the white oak, and the red oak, but none for the oak in general,—still less for tree in general. The indigenes of Brazil can point out the different parts of the body, but not the body as a whole (Lubbock). Among several tribes of Oceania, a special word is employed for the tail of a dog, another for the sheep’s tail, and so on, but they have no designation for tail in general. Again, there is no common term for the cow, but there are distinct words for red, white, or brown cows (Sayce).

There are, however, cases of very clear progress in generalisation; the significance of a word extends itself; from specific it becomes generic. This metamorphosis exists in vivo among the Finns and Laplanders. The former have a name for the smallest stream, and none for river; originally again there was a term for each finger, none for finger in general; but latterly the term used for thumb alone has come to designate the fingers collectively. Among the second race, certain tribes who had a special denomination for each kind of bay, have now adopted one that serves for all kinds (Max Müller).

The same holds good of the poverty of the adjective, the abstract term proper. The case of the Tasmanians has often been quoted, how they could only express qualities by concrete representations: hard = like a stone; long = legs; round = like a ball, like the moon, etc. (Lubbock). A less familiar case, termed by linguists “concretism,” is met with even in certain more developed idioms, like a survival of the time when the mind was unable to detach itself from the concrete, or to forego a complete and detailed qualification. Instead of saying ten merchants, five hens, the idiom is merchants ten men, hens five birds, and so on for similar cases.

The verb is able to express all degrees of abstraction and of generalisation as well as the adjective and substantive. At this period, it exactly repeats the type (as described above) of the substantive with its burdensome multiplicity,—for want of a generalisation simple enough, according to our judgment. The North American Indians have special words for saying: to wash one’s face, another person’s face, the linen, utensils, etc.: in all, thirty words, but none for washing in general. So, too, for eating bread, fruits, meat, etc., striking with the hand, foot, axe, etc., for cutting wood, meat, or any other objects: for all these there are special terms, but none for saying simply, to eat, to knock, to cut (Sayce, Hovelacque.) On the other hand, we note a case of transition, analogous to that of the Lapps and Finlanders. Certain tribes in Brazil have a few verbs of general, simple significance: eat, drink, dance, see, etc., even love, thank, etc. (Lubbock).

We need not multiply examples; these will suffice to throw into relief the extreme impotence in generalising, so soon as the mind loses its hold on the concrete. We might also recall the difficulty so often experienced by missionaries. They find it almost impossible, even by creating new words, or by changing the meaning of others, to translate the sacred books into these idioms, from their paucity of concrete terms.

2. The numeration, taking its development as a whole, appears to sub-divide into three principal periods: concrete numeration, as studied above, in animals and children; concrete-abstract numeration, with which we are now occupied; purely abstract numeration, which we shall examine later, as translated into organised arithmetic.

We have seen that speech at its origin was so humble as to need gesture to complete and to elucidate it. During its concrete-abstract period, numeration is in an analogous position. At first its extension is very limited: it progresses slowly and painfully from unity. Further, it can operate only when sustained by the concrete; it must have a material accompaniment. Counting is accomplished by the enunciation of words, with the aid of enumerated objects, as perceived at the same time, or with that of the fingers: which, let it be remarked, is the first essay in substitution. There is simultaneously concrete or digital, and verbal numeration.[74]

We know that many Australian and South American tribes can count verbally to two only; some say two-one = three; two-two = four; others by the same process arrive at six (two-three = five, three-three = six): everything else is “much.” For the most part they count without words, with the aid of fingers or of articulation; even when they employ words, the two numerations—digital and verbal—are performed simultaneously.[75]

This manner of counting is in first degree concrete; the concrete-abstract form is only there in embryo. A great advance, made early enough in many tribes, consisted in counting by five, taking the hand (five fingers) as a new unit, superior to the simple unit. Then: one hand = 5; two hands or half a man = 10; two hands, one foot = 15; two hands, two feet, or a man = 20. Such is the evident origin of the quinary, decimal, and vigesimal numerations. Sometimes fingers, as instruments of numeration, have been replaced by objects of a typical number. Ex.: 1 = moon or sun; 2 = the eyes or legs, etc.

However varied these processes (of which only a few have been mentioned) in different races and periods, they are fundamentally identical to the psychologist. They may be reduced to this; numeration is performed more particularly with the aids of sensible perceptions; words are but an insignificant accompaniment, a superfluity—existing only as a proliferation—of so little utility that they are for the most part neglected.

Though it is less often spoken of, we may remark that the measure of continuous quantity passed through the same concrete-abstract phase; and here it appeared at a somewhat early stage, owing to practical and social wants. Hence we find at the outset, the foot, the finger, the thumb (inch = Fr. pouce), the palestra (four fingers’ length), span, cubit (arm’s reach = coudée), fathom, etc., the stadium (distance a good runner could cover without stopping).[76] The concrete character of all these measures is obvious. Again, there are survivals in certain current locutions, such as a day’s journey. More than this; they have a human character, their standard and starting-point being, at least at the outset, certain parts of the body, or a determined sum of muscular movements. Little by little they lost their original significance, progressing through centuries towards our metrical system the type of a scientific, deliberate, rationally abstract system, as far as possible liberated from anthropomorphism.

The reader will probably obtain a more definite idea of the nature of these lower forms by recapitulating the examples cited, than from any long dissertation. Is their intellectual level very superior to that of the generic image? This question is doubtful. At times the only distinction between them is the presence of the word: at the present stage it makes but a poor figure,—yet with all its modesty, it augurs a new world wherein it is to be of prime importance.

II.

We now pass to a study of transition. In ascending from the lower to the higher forms of abstraction, we traverse the intermediate region between the states directly superposed upon generic images, and the higher concepts. In fact, we shall to some extent have to penetrate into this extreme region, before the close of the chapter.

At the risk of repetition, we must first indicate the characteristics by which the general notions we are at present concerned with are distinguished from the abstractions above and below them. To recapitulate briefly: In the concrete-abstract phase (which we are leaving) the general notion—so-called—is constituted by concrete elements, plus words, whose substitutory office is weak or null.

In the abstract phase (upon which we are entering) the concept is constituted by an evoked or evocable image, which may exhibit every degree from clear representation to the pure schema, plus the word that now becomes the principal element.

In the phase of higher abstractions (to be studied later), no sensory representation arises, or should any such appear, reflexion would find in it only a dubious support, often an obstacle: the word meantime has acquired absolute supremacy in consciousness.

Taken as a whole, psychological development exhibits a complex phenomenon, a binary compound, in which one element is always increasing, the other as steadily decreasing. Words pass from nonentity to autocracy; the concrete from supremacy to nonentity.

We must now return to the higher forms of intermediate abstraction, since we may not content ourselves with any purely theoretical determination. Characteristic examples must be selected; and here we find a certain embarrassment. Does our choice fall on numeration? Yet on leaving the concrete-abstract period, this at once finds its formative law, and introduces us to pure abstraction. Are we to select language? This procedure might seem to be appropriate, seeing that the general ideas with which we are occupied constitute the substrata of our highly civilised modern languages, when, on the other hand, the more developed concepts (of mathematics, metaphysics, etc.) are only found rarely and incidentally. One might even plunder the dictionary, extracting all general terms, with elimination of those that are purely scientific, and classification of the former according to their increasing degree of generality. But this method, besides being very laborious and incapable of reduction to a clear statement for the reader, would suffer the cardinal defect of being arbitrary. How, indeed, could any common measure be established for all these general terms, issuing from the most diverse sources of human activity?[77]

But the best method would seem to be that of taking as our basis the classifications of the naturalists, following their development historically. Here we have the advantage of positive documents, since these refer to concrete beings, and are formed according to characters observed empirically. They create, namely, an ascending progress from the individual to the more general notions, by a methodical process of filiation; they operate upon living beings, or objects of the same nature, having consequently a common standard. The history, even in brief, of these classifications is instructive: it shows the progressive passage of concrete-abstract ideas to more and more abstract concepts, from a statement of gross resemblances to the quest after subtle similarities, from the period of assimilation to that in which dissociation predominates.

Among these different classifications, we may select those of the zoologists, since they appear to be the most numerous, most complete, and best elaborated. For the rest, the succeeding observations apply equally, mutatis mutandis, to the classifications of the botanists. We need scarcely add that our study is strictly psychological, that its object is not the absolute value of classifications, but the determination of the processes followed by the human mind, in proportion as the zoölogical taxonomy has constituted itself.

At the outset we find a pre-scientific period as to which we know little; for these essays in classification differ, according to times and races. The Bible, Hindu literature, the primitive poets and historians of Greece, do however provide sufficient indications of the manner in which man originally classified other living beings. The repartition was usually made in three great categories, according as the animals lived in the water, or upon the earth, or flew in the air. The subdivisions are remarkable. Thus, among terrestrial animals, there are some that walk, and some that climb: in this last group there is a mixture of articulate creatures, of molluscs, reptiles and amphibians. Among aerial animals, we find birds, and many flying insects. These primitive classifications are based upon perception far more than on abstraction, or at any rate rest upon superficial resemblances. The habitual environment, air, water, earth, determines the cardinal classes. Some easily apprehended characteristic makes the subdivisions: e. g., flight (birds, insects), locomotion (walking, climbing). The method employed is hardly superior to that by which generic images are formed; and in the order of classification, this point corresponds with the concrete-abstract period of primitive languages, numerations, and religions, i. e., to a gross generalisation fixed by a word.

The scientific period begins with Aristotle. It has been affirmed that he owes numerous points to predecessors whom he fails to mention: this is a historical matter of no interest in the present connexion. With him, or under his name, we have the commencement of comparative anatomy which involves a preliminary labor of analysis, unknown in the pre-scientific period, and marking the transition from apparent and superficial to profound and essential resemblances. His classification is of course imperfect, often inconsistent; it bears the impress of an epoch of transition.

His terminology is poor, unstable, floating. He distinguishes two sorts of groups only: the genus (γένος) and the species (εἶδος). “But the term γένος has the least constant significance: it serves as the indistinct designation of any group of species, however great its extension, as well what we now term classes, as other lower groups.”[78] Sometimes however Aristotle speaks of large genera (γένη μέγαλα) and of very large genera (γένη μέγιστα), without any precise denotation. It has been said that penury of words was an obstacle to him: yet this is hardly a plausible reason, seeing that he found means to create the word ἔντομα to designate insects. The true obstacle was the insufficient determination of character.

Again, independently of nomenclature, “while Aristotle knew a fairly large number of animals, the notion of grouping them in definite order, which should express their greater or less degree of similarity, does not appear to have presented itself to his mind. Hence he did not attempt what we call classification. He compares different animals together, by every possible means, and endeavors to reduce the result of his comparisons to general propositions.” In this way he arrives at relations which are sometimes important, sometimes without importance. For example: among animals, some have blood, some lymph, which takes its place: this division, notwithstanding the error on which it is based, corresponds broadly speaking with the distinction between vertebrates and invertebrates. Animals “which have blood” are subdivided into viviparous and oviparous. Further, animals that fly are ranged in three categories, according as their wings are feathered (birds), or formed by a fold of skin (bats), or dry, thin, and membranous (insects). Then there is a division of animals into aquatic and terrestrial, social and solitary, migratory and sedentary, diurnal and nocturnal, domestic and wild, etc.

In sum, there is co-existence of two processes: one scientific, implying a preliminary analysis; the other of common observation, which does not sensibly differ from concrete-abstract classifications; and the idea of a hierarchy formed by abstraction of abstracts, by a systematic arrangement of the animal kingdom, has not yet made its appearance. Yet Aristotle’s work, just by reason of its composite nature, is interesting to the psychologist who studies the evolution of the faculty of abstracting and generalising.

We may pass over two thousand years, during which no progress was made, till we come to Linnæus. “He was the first man who distinctly conceived the idea of expressing, under a definite formula, what he believed to be the system of nature.” His nomenclature is fixed. Under the names of classes (genus summum), orders (genus intermedium), genera (genus proximum), species, varieties, he proposes subdivisions of decreasing value, embracing a greater or less number of animals which all present in common more or less general attributes. He pursues the research after fundamental characteristics, and essential similarities, incessantly correcting his first results. Thus it is only at the eleventh edition of his Systema naturæ that the class of “Quadrupeds” is converted into Mammals: the Cetacea are included in this class, and no longer placed among the fish, as also bats, which were formerly classified with birds, etc.[79] Whatever their objective value, we have here a true system of rational concepts.

We may instance Cuvier for the clearness with which he separates the predominant and subordinate characteristics: “If,” he says, “we consider the animal kingdom on the principles just laid down, regarding only the organisation and nature of the animals, instead of their size and utility, according to our knowledge of them, or the sum of accessory circumstances, we find that there are four principal forms, four general plans, if we may so express ourselves, on which all animals seem to have been modelled,” etc. These four branches (a new word created by him), which he held to be irreducible, were the Vertebrata, Articulata, Mollusca, and Radiata.

Finally, since the progress of consecutive abstraction and generalisation consists in incessantly seeking out extracts of extracts, and simplifications of simplifications, the natural movement of the mind tends fatally towards pure unity as its supreme end. This last phase belongs to the nineteenth century, and still more to the contemporary epoch. It comes from various sources, and has assumed different forms:

1. Speculative in the school of Schelling. To Oken, the highest representative of this view, man is the prototype and measure of animal organisation; all other animals are constructed after his pattern. “Their body is in some sort the analysed body of a man; the human organs live, whether in isolation, or in different combinations, in the state of independent animals. Each such combination constitutes a class.”

2. Embryological, according to the labors of Von Baer. While Cuvier, in classification, brought anatomy and morphology to the front, a new system now appears, founded upon development only; the science of embryology. To be accurate, Baer’s conception was not unitary, since it admitted four types: peripheral (radiate), massive (molluscan), longitudinal (articulated), bi-symmetrical (vertebrate). But little by little, the oft-substantiated principle asserted itself and found firm footing among his successors: the animal with the highest organisation passes, during its individual development, through phases which, in less highly evolved beings, are permanent states; or, more briefly, among the higher animals, ontogenesis is a repetition of phylogenesis.

3. Transformist. The boldest partisans of this view, e. g., Haeckel, adopt a rigorously unitary conception: all the innumerable examples of the animal kingdom have issued from one common stock.

In all there is a fundamental trend of the mind towards the idea of original unity. It is unimportant for the moment to examine whether this concept of ideal unity (we might also recall the vegetable ideal of Goethe, and the vertebrate ideal of Richard Owen) is a delusion, or a true apprehension: we shall return to this later, in discussing the objective value of the notions of genus and species (Chap. V. § vi). At this point, the subjective psychological process alone is relevant to our purpose.

This review has no pretensions at being even an abridged history of zoölogical classifications. It merely aims at showing by facts, (1) how a hierarchy of concepts is constituted, and in the travail of centuries passes from the period of generic images to the ideal of embryological unity, common to all beings; (2) how the work of dissociation and analysis has always gone on, and multiplied, in quest of similarities more and more difficult to discover—often indeed fragile or dubious—to stop at unity only, the supreme abstraction.

We are now at the threshold of the last period of abstraction, that of complete symbolism, and it is not without interest to note that what passes in the theoretical order has its equivalent in another form of human activity—the practical order—where the mechanism of exchange is again developed by the aid of an ever-increasing substitution. Thus, at the lowest stage, all commercial transactions are reduced to truck, to exchange by barter. The concrete for the concrete is the method of primitive peoples. An immense step is taken when this rudimentary process is succeeded by the employment of precious metals. A substitutory value is taken as the common measure of other values. At the outset, silver and gold, in the form of powder or of small bullion, were weighed out by the contractors for each particular transaction. Next, this inconvenient procedure was replaced by coined money, issued under the control of an officer, or of the social aggregate, thus conferring a general value on the instrument of exchange. Lastly, at a much later period, bills of exchange, bank-notes, and numerous forms of letters of credit, were substituted for gold and silver; so that a sheet of paper worth less than a centime may become the symbol of millions and tens of millions.

This resemblance of the two cases is by no means fortuitous. It is based upon identity of psychological process, namely a substitution of ascending degrees, an ever increasing simplification, whether in the order of speculative research, or in the department of commercial transaction: and just as paper tokens, unless financially convertible into objects of consumption, for use or luxury, are nonentities that can accumulate in the bank without the gain of anything more than a simulacrum—so, if the highest symbols of abstraction cannot be reduced to the data of experience, we may, as too often occurs, accumulate, manipulate, build up concepts, and still be in a state of permanent intellectual bankruptcy.