The Online Library of Liberty

A project of Liberty Fund, Inc.

• Preface.
• Part I.: Special Analysis.
• Chapter I.: A Datum Wanted.
• Chapter II.: The Universal Postulate.
• Chapter III.: Its Corollaries.
• Chapter IV.: Our Present Position.
• Part II.: Special Analysis.
• Chapter I.: Compound Quantitative Reasoning.
• Chapter II.: Compound Quantitative Reasoning (continued).
• Chapter III.: Imperfect and Simple Quantitative Reasoning.
• Chapter IV.: Quantitative Reasoning In General.
• Chapter V.: Perfect Qualitative Reasoning.
• Chapter VI.: Imperfect Qualitative Reasoning.
• Chapter VII.: Reasoning In General.
• Chapter VIII.: Classification, Naming, and Recognition.
• Chapter IX.: The Perception of Special Objects.
• Chapter X.: The Perception of Body As Presenting Dynamical, Statico-dynamical, and Statical Attributes. ∗
• Chapter XI.: The Perception of Body As Presenting Statico-dynamical and Statical Attributes.
• Chapter XII.: The Perception of Body As Presenting Statical Attributes.
• Chapter XIII.: The Perception of Space.
• Chapter XIV.: The Perception of Time.
• Chapter XV.: The Perception of Motion.
• Chapter XVI.: The Perception of Resistance.
• Chapter XVII.: Perception In General.
• Chapter XVIII.: The Relations of Similarity and Dissimilarity.
• Chapter XIX.: The Relations of Cointension and Non-cointension.
• Chapter XX.: The Relations of Coextension and Non-coextension.
• Chapter XXI.: The Relations of Coexistence and Non-coexistence.
• Chapter XXII.: The Relations of Connature and Non-connature.
• Chapter XXIII.: The Relations of Likeness and Unlikeness.
• Chapter XXIV.: The Relation of Sequence.
• Chapter XXV.: Consciousness In General.
• Chapter XXVI.: Results.
• Part III.: General Synthesis.
• Chapter I.: Method.
• Chapter II.: Connexion of Mind and Life.
• Chapter III.: Proximate Definition of Life.
• Chapter IV.: The Correspondence Between Life and Its Circumstances.
• Chapter V.: The Degree of Life Varies As the Degree of Correspondence.
• Chapter VI.: The Correspondence As Direct and Homogeneous.
• Chapter VII.: The Correspondence As Direct But Heterogeneous.
• Chapter VIII.: The Correspondence As Extending In Space.
• Chapter IX.: The Correspondence As Extending In Time.
• Chapter X.: The Correspondence As Increasing In Speciality.
• Chapter XI.: The Correspondence As Increasing In Generality.
• Chapter XII.: The Correspondence As Increasing In Complexity.
• Chapter XIII.: The Co-ordination of Correspondences.
• Chapter XIV.: The Integration of Correspondences.
• Chapter XV.: The Correspondences In Their Totality.
• Part IV.: Special Synthesis.
• Chapter I.: The Nature of Intelligence.
• Chapter II.: The Law of Intelligence.
• Chapter III.: The Growth of Intelligence.
• Chapter IV.: Reflex Action.
• Chapter V.: Instinct.
• Chapter VI.: Memory.
• Chapter VII.: Reason.
• Chapter VIII.: The Feelings.
• Chapter IX.: The Will.

CHAPTER XII.

THE CORRESPONDENCE AS INCREASING IN COMPLEXITY.

§ 153. Another change in our stand-point, affords us a view of vital progress, which, though not coextensive with foregoing ones, has much in common with them. As we saw that the extensions of the correspondence in Space and in Time, were in part reciprocal and in part not so; as we saw that the increase of the correspondence in Speciality, while to some degree comprised under the extensions in Space and Time, includes very much beside; so we shall find that while, throughout a certain range of cases, progress in Complexity is the same thing as progress in Speciality, yet neither includes all that the other does. Much of the early advance in Speciality does not imply advance in Complexity; and the higher forms of the advance in Complexity cannot without straining, be comprehended under advance in Speciality. But let us glance at the facts.

§ 154. In the progress from an eye that appreciates only the difference between light and darkness, to one which appreciates degrees of difference between them, and afterwards to one which appreciates differences of colour and degrees of colour—in the progress from the power of distinguishing a few strongly contrasted smells or tastes, to the power of distinguishing an infinite variety of slightly contrasted smells or tastes—in the progress from that lowest form of hearing, consisting simply in a response to any violent tremor of the surrounding fluid, to those higher forms of it in which differences of loudness are recognized, and by and by differences of pitch and timbre—in all those cases which present merely a greater ability to discriminate between varieties of the same simple phenomenon; there is increase in the speciality of the correspondence without increase in its complexity. The insect which lays its eggs only on a plant having a particular odour; and the bird which is alarmed by a tone of a certain pitch, but not by one of another; exhibit an adjustment of inner to outer relations, as simple as that seen in the snail which withdraws into its shell on being touched. Though the stimulus responded to is more special, it is not more complex. In each case a single undecomposable sensation, is followed by certain muscular actions: and though these muscular actions are more intricate in the higher creatures than in the lower; yet the relation between the antecedents and consequents, is very nearly, if not quite, of the same order. But where the stimulus responded to, consists, not of a single sensation but of several; or where the response is not one action but a group of actions; the increase in speciality of correspondence results from an increase in its complexity.

In the development of vision we see this repeatedly illustrated. When, in addition to the usual relation between opacity and solidity, first responded to, there arises a response to the relation between solidity and the power to reflect light—when differences in the amounts and qualities of reflected light come to be recognized in connection with differences of bulk—when there arises a power to identify objects, not only by colour and size conjoined, but by form—when surrounding things are grouped in more and more numerous classes, that agree with each other in such and such peculiarities, but differ in others; it is manifest that each successive stage implies the appreciation of larger clusters of attributes. The impression received by the organism from each object, is a more complex impression—is increasingly heterogeneous. And when not only colour, size, and shape become cognizable, but also direction in space, distance in space, motion, kind of motion, direction of motion, velocity of motion—when, as by a falcon swooping on its quarry, all these external relations are simultaneously responded to; it is clear that the guiding perception must be compounded of many elements. There is no need to dwell on this truth as further exemplified in the evolution of the other senses; nor to trace up in detail that yet higher complexity which results when the several senses are employed together. It suffices to cite an extreme case, such as that afforded by the mineralogist, who, in identifying a mass of matter as of a kind fitted for a certain use, examines its crystalline form, its colour, texture, hardness, cleavage, fracture, degree of transparency, lustre, specific gravity, taste, smell, fusibility, magnetic and electric properties, &c., and is decided in his conduct by all these taken together—it suffices to cite such a case as this, to show that throughout all the higher range of cases, increase in the speciality of the correspondence involves increase in its complexity.

§ 155. But, as already hinted, we eventually reach an order of correspondences in which the speciality and the complexity are no longer co-ordinate. A further advance in speciality is achieved by a much more than proportionate advance in complexity. In these cases, the adjustment of particular actions to particular circumstances, involves a far more extensive pre-adjustment of inner relations to outer relations, than is directly displayed. Let us look at an example or two.

The archer, who points his arrow, not at the object he seeks to hit, but above it, and who varies the angle of elevation according as the object is far or near, exhibits something more than a special response to special stimuli; for his procedure implies recognition of the fact, that bodies projected through the air, descend towards the earth, and that the amount of their descent has some relation to the distance traversed. Besides a correspondence with certain sensible relations in the environment, there is implied a correspondence with the law of certain other relations, not then present to the senses. Again, to take a more marked case:—the engineer who erects a suspension-bridge competent to bear a specified strain, is enabled to adjust his actions to the requirements, less by his inspection and measurement of the river to be crossed, than by his knowledge of the strength of wrought iron, of the properties of the catenarian curve, of the composition of forces—his acquaintance with the universal truths of number, geometry, mechanics. In these cases the complexity of the correspondence is greatly in excess of the speciality. To bring out this fact by a contrast:—It might fairly be said that the Indian fish which catches insects flying over the surface by hitting them with jets of water, exhibits a correspondence as special as that seen in the archer; but considering that in the fish, the action implies nothing more than an automatic connection between certain visual impressions and certain muscular contractions—any modification of the one itself causing a modification of the other—it cannot be held that there is anything like the same complexity of correspondence. And similarly, though it might be plausibly argued that the strength of a spider's web is as specially adjusted to the demands to be made upon it, as is that of the engineer's suspension-bridge; yet it will not be contended that there is any comparison between them in respect of the variety and elaborateness of the actions implied.

If now we inquire whence arises this excess of complexity; we find that it is caused by the addition of generalities to specialities. Each of these higher correspondences displaying what we call rationality, implies an adjustment of inner relations not simply to the concrete outer relations then present; but to one or more of those abstract relations among external things, which previous experience has generalized. And as we advance to correspondences of still greater and greater complexity, we see that their leading characteristic is the increasing number of the abstract relations recognized, and involved in the process of adjustment. In these cases, there is a response, not simply to the particular phenomena presented in one part of the environment; but there is, as it were, a simultaneous response to sundry of the general phenomena presented by the environment at large. When we reach the highest achievements of science, as especially exemplified in astronomy, it becomes obvious that an exact adaptation of the actions of the organism, to special actions in the environment, implies the pre-establishment of general relations in the organism, parallel to all those general relations in the environment which are in any way implicated with the phenomenon.

§ 156. There seems no place fitter than this, for drawing attention to the fact which has not yet been noticed, and which it is yet very important to notice, that there is a more or less constant ratio maintained between the impressibilities and the activities of the organism, in so far as their complexity is concerned. Considered under its most general form, every correspondence effected between the organism and the environment, involves two things—the reception of one or more impressions, and the performance of one or more appropriate motions. In the lowest animal types, we see a touch followed by a withdrawal of the part touched—a single impression followed by a single action. Gradually as we ascend, we observe an ability to receive increasingly complicated impressions, and to perform increasingly complicated actions. And the truth here to be observed, is, that the heterogeneity of the stimuli that can be received, is in general proportionate to the heterogeneity of the changes that can be displayed.

Before passing to the rationale of this, it may be well to remark, that from a teleological point of view, no other arrangement is admissible. As every advance in the correspondence between the organism and its environment, consists in the addition of some further internal adjustment to some further external relation; and as the ability to recognize the external relation is useless unless there is an ability to appropriately modify the conduct; it is clear that for the better preservation of life, the passive and active elements of the correspondence must progress together in speciality and complexity. A power to perceive the position of an object in space, must be accompanied by a power to specialize the movements; otherwise it can be of no service. The recognition of certain forms, colours, and motions as those of an enemy, will not prevent destruction unless it be followed by such velocity of motion, such doublings, such leaps, as the enemy may be eluded by. The discrimination shown by a bird in the choice of materials for its nest, is so much faculty thrown away, unless there be sufficient constructive skill for nidification. It will not benefit the savage, to discover at what seasons and what times of the tide particular fish are to be caught, unless he has dexterity enough to make and use the apparatus needful for catching them. And so throughout, it must on the average happen, that every further differentiation of the perceptions, opening the way for a further differentiation in the actions, fails of its purpose unless an ability further to differentiate the actions is associated with it.

Leaving, however, all thought of ends to be subserved, we shall find the true explanation of this connection between progress in the impressibilities and progress in the activities, is simply that each necessitates the other—that they so act and react, that the advance of either involves the advance of both. The general relation between irritability and contractility, which, in the lowest types of animal life, constitute one indivisible phenomenon, is a relation which the sensitive and the active divisions of the organism, maintain throughout all their complications. They are co-ordinate in their origin; they are co-ordinate in their manifestations; they are co-ordinate in their progress. As certainly as the nervous and muscular systems make their appearance together; as certainly as, throughout the whole animal kingdom, they preserve a general parallelism in degree of development; so certainly is there an indissoluble connection between their respective functions in point of advancing complexity.

A general conception of this law will best be obtained by regarding the two functions under their most abstract forms—sensation and motion. Given an organism with certain sensory and motor faculties, and what must happen from the increase of either? Higher powers of motion and locomotion, must unavoidably bring the organism into relation with a greater number of objects; and must so result in multiplying its impressions. Higher sensitiveness in the organism, must unavoidably entail more frequent stimuli to action; and must so multiply its motions and locomotions. Again;—The more varied a creature's activities, the more varied must be the relations in which it puts itself towards surrounding things; and hence the more varied must be the modes in which surrounding things affect it. And, conversely, the greater the variety of impressions receivable from surrounding things, the greater must be the number of modifications in the stimuli given to the motor faculties; and hence, the greater must be the tendency towards modified actions in the motor faculties. Thus, in respect both of activity and complexity, the progress of each is involved with the progress of the other.

But the necessity of this simultaneous development of the directive and executive faculties, will be most clearly seen on analyzing a few cases. Take as one, the ability to recognize direction in space. At first this may be thought to imply a development simply of the sensitive part of the nature—simply an expansion of the retina sufficiently great to admit of its several parts being separately affected by images falling upon them. But a little consideration will show, that something more is required than ability to perceive differences in the position of the image on the visual tract. Taken alone, these differences are meaningless: they come to have meaning, only when they are severally connected in the organism with those differences of motion required to bring the surface into contact with the things seen. As all psychologists admit, mere ocular impressions do not of themselves give any ideas of space. These arise, only when, by a growing experience, the impressions are referred to objects that can be touched by special muscular adjustments. Direction, therefore, cannot be perceived until there is not only a motor apparatus, but one so far developed as to effect specialized movements. And thus, the ability to perceive direction, and the ability to take advantage of the perception, are necessarily connate. The recognition of distance, of velocity, of bulk, of shape, so obviously imply the like conditions, as merely to need mention. Again, differences of light and shade cannot be known to indicate variations of surface, until these variations have been disclosed by corresponding variations in the adjustments of the muscles; and so, complex muscular adjustments must be possible, before complex variations of light and shade can be interpreted. No definite idea of weight, as connected with visual appearances, can be arrived at, until there is a power of lifting, either by the jaws or limbs. Nor can differences of hardness and texture be assigned to surrounding objects, faster than the manipulative organs are perfected. And indeed, as these last instances suggest, it is not simply that the impressions made upon the senses require to be connected with the muscular experiences, before their meanings can be made out; but it is that the impressions themselves, in their higher forms, cannot be received without muscular aid. Perfect vision implies a focal adjustment of the eyes, an adjustment of their axes to the requisite convergence, a turning of them both towards the object, sometimes a turning of the head in the same direction, and sometimes also a turning of the body; all of which preparatory acts are performed by the muscles; and the last ones, not by the muscles of the eye, but by those of the body at large. Neither taste nor smell are possible unless the muscles of the tongue and the chest do their parts. Even hearing is imperfect unless the membrana tympani is strained by its muscles into concord with each successive sound. But above all, the knowledge acquired through the sense of touch, is especially dependent upon the motor apparatus. The mere existence of a sensitive skin, is but a small part of the requirement; as any one may prove by closing his eyes and applying his bare arm or leg to an unknown object. For the tactual impressions to be such as will give ideas of extension, form, solidity, this sensitive skin must be distributed over surfaces capable of deriving simultaneous or rapidly succeeding sensations from different parts of the things touched; and these sensations must be combined with those muscular sensations accompanying the simultaneous and successive adjustments of the sensitive surfaces. There must be limbs to effect the larger and simpler adjustments; and appendages to them to effect the smaller and more elaborate ones. And only in proportion as these motor agencies become complex and complete, can there be completeness and complexity in the tactual perceptions. But these motor agencies—these limbs and appendages, with all the muscles they are moved by, are also the locomotive and manipulating organs; and the same elaborateness of structure which fits them to receive compound impressions, also fits them to perform compound operations. Thus, the evolution of the sensitive or directive apparatus, is inseparably involved with the evolution of the muscular or executive apparatus.

And here we may fitly notice a group of facts serving to illustrate this general law—facts exhibiting in the concrete, this constant relation between the impressibilities and the activities in respect of their complexity. I refer to the sundry striking instances, presented throughout the animal kingdom, of unusual sagacity coexisting with unusual development of the tactual organs. Why touch, which is in itself the simplest and earliest sense, should, in its higher forms, be more than any other sense associated with the advance of intelligence, will perhaps seem difficult to understand. The explanation lies simply in the fact, that tactual impressions are those into which all other impressions have to be translated, before their meanings can be known. If we contemplate the general relation subsisting between the organism and surrounding objects, we see that before they can affect it, or it can affect them, in any important way, there must be actual contact. Assimilation, respiration, locomotion, the destruction of prey, the escape from enemies, the formation of nests and burrows, the bringing up of young—all the essential functions, when considered in their ultimate natures, imply mechanical action and reaction between the organism and its environment. The space-penetrating faculties serve but as guides to this mechanical action; and the impressions they receive, are primarily used but as symbols of tangible properties and relations. Hence it happens, that only as fast as the mechanical impressions, recognized by the muscles and the skin, become varied and complex, can there be a complete translation of the varied and complex impressions recognized by eyes, ears, and nose. The mother tongue must be as copious as the foreign; otherwise it cannot render all the foreign meanings. And thus, as seen in the facts referred to, a highly elaborated tactual apparatus comes to be the uniform accompaniment of superior intelligence. But let us look at these facts.

Just to show that each great family of the animal kingdom supplies them, I may mention in passing, that the Cephalopoda, which in point of sagacity are far in advance of other Mollusca, are structurally distinguished from them in having several arms by which they can grasp an object on all sides, at the same time that they apply it to the mouth; and again, that the crabs, which similarly stand at the head of the sub-kingdom Articulata, can bring their claws and foot-jaws simultaneously to bear upon anything they are manipulating. But merely glancing at these, let us content ourselves with examples supplied by the vertebrate tribes. It will be admitted that, of all birds, parrots have the greatest amount of intellect. Well, if we examine in what respect they are structurally most distinguished from other birds, we find it to be in development of the tactual organs. Few birds have such power of prehension with the feet, as to be able to grasp and lift up an object with the one foot, while standing on the other. The parrot, however, does this with ease. In most birds the upper mandible is scarcely at all moveable. In the parrot it is moveable to a marked extent. Generally, birds have the tongue undeveloped, and tied down close on the lower mandible. Parrots, however, have it large, free, and in constant employment. Above all, that which the parrot grasps in its claw, it can raise to its beak; and so bring both mandibles and tongue to bear upon what its hand (for it is practically a hand) already touches on several sides. A moment's consideration suffices to show, that no other bird approaches to it in the complexity of the tactual impressions it can receive; and thus, advance of the directive faculties is manifestly involved by advance of the executive ones.

Among quadrupeds, again, it is unquestionable that as a general rule the Unguiculata, or those that have the limbs terminating in separate digits, are more intelligent than the Ungulata, or hoofed animals. The feline and canine tribes stand psychologically higher than cattle, horses, sheep, and deer. Now it is obvious that feet furnished with several sensitive toes, are capable of receiving more complicated impressions than feet ending in one or two masses of horn. While, by a hoof, only one side of a solid body can be touched at once; the divided toes of, for example, a dog, can simultaneously touch the adjacent sides of a small body, though not the opposite sides. And if we further bear in mind that the higher kinds of toed quadrupeds, while they cannot grasp with their feet, can nevertheless use them for holding down what they are tearing or gnawing with the teeth; we see that they can recognize tangible relations of considerable complication. Add to which the fact, that when, among the hoofed animals, we meet with any marks of sagacity, as in the horse, we find that the lack of sensitive extremities is in some measure compensated for by highly sensitive and mobile lips, which have considerable power of prehension. And here, indeed, we are naturally reminded of the most remarkable, and perhaps the most conclusive instance, of this connection between development of intelligence and development of the tactual organs—that seen in the elephant. I say most conclusive, because the elephant is markedly distinguished from allied tribes of mammals, alike by its proboscis, and by its high sagacity. The association between the operative and cognitive faculties stands out the more conspicuously, from the endowment of both being exceptional. On the intellect of the elephant there is no need to dwell: all know its superiority. The powers of its trunk, however, must be enumerated. Note first, its universality of movement, in respect of direction. Unlike the ordinary mammalian limbs, whose motions are more or less confined to the vertical plane, its flexibility gives it as wide a range of positions as the human arm can take—wider, indeed, than can be taken by a single arm: and thus the elephant can ascertain the relations in space, both of its own members and of surrounding things, more completely than all other creatures, save man and the higher quadrumana. Again, the trunk can grasp bodies of every size, from a pea to a tree stump; and by this means can ascertain the tangible forms of a greater variety of objects than any of the lower mammalia. The finger-like projection with which the trunk terminates, receives impressions of the minor variations of surface; and so, textures and the details of shape can be made out, as well as general extension. Moreover, the complete prehensile power, giving ability to lift bodies of many sizes and natures, opens the way to a knowledge of weight, as connected with visible and tangible properties. The same power of prehension, used as it habitually is for the breaking-off of branches, brings experiences of the tenacity and elasticity of matter; and when employed, as these branches often are, for driving away flies, the swinging of them about must supply vague impressions even of momentum—impressions which the ability to throw small bodies (as gravel over the back) must tend to strengthen. Further, the trunk's tubular structure fits it for a number of hydraulic experiments, and so gives a knowledge of the mechanical properties of water, such as no other quadruped can attain to; and this same peculiarity, rendering it possible to send out strong blasts of air, producing motion in the light bodies adjacent, opens the way to yet another class of experiences. Thus, the great diversity of tactual and manipulatory powers possessed by the elephant's proboscis, is not less remarkable than is the creature's high sagacity—a sagacity which, dwelling in so ungainly a body, would otherwise be altogether inexplicable.

Passing to the quadrumana, we find repeated, under other forms, this same relation between development of the intelligence, and development of the tactual appendages. It is seen not only in the contrast between them and inferior mammals; but it is seen in the contrasts between the subdivisions of the quadrumana themselves. The prehensile and manipulatory powers of the lower genera, are as imperfect as are their mental powers. As we advance to the highly intelligent anthropoid apes, we find the hands so modified as to admit of more complete opposition of the thumb and fingers; the bones of the forearm so articulated as to give the hand a power of rotation; the arms attached to the body in such a manner as allows them an increased range of lateral movement. And when, as in all the more perfect of the class, the structure of the fore-limbs is so complete, that an object can be grasped in one hand, while it is being manipulated with the other, or by the lips and teeth—can be held at the most convenient distance from the eyes—can be applied to any part of the body, or any neighbouring object—it is manifest, that more complex perceptions, of size, shape, structure, texture, hardness, weight, flexibility, tenacity, in their various combinations, can be received, than are possible to creatures whose limbs are less elaborately constructed. And thus the mutual dependence of the operative and cognitive faculties becomes clearly apparent.

How, in man, both exist in yet higher perfection, scarcely needs saying. As contemplated from an obverse point of view, the connection between them is abundantly exemplified in works on natural theology. All that it is desirable here to notice, is, the extent to which, in the human race, this perfection of the tactual apparatus has subserved the highest processes of the intellect. It is not simply that the tangible attributes of things have been rendered completely cognizable by the complex and versatile adjustments of the human hands—it is not simply that the greater knowledge of objects thus reached, opened the way for the making of tools, and consequently for agriculture, building, and the arts in general—it is not simply that by these were made possible, the settled and populous societies without which none of the higher forms of intelligence can be attained to; but it is, that the manipulative powers directly underlie the sciences, including even the most remote and abstract. All developed science, consisting as it does of quantitative prevision—dealing as it does with measured results, is lineally descended from that simplest kind of measurement achieved by placing side by side the bodies held in the hands. Our knowledge of the forces governing the solar system, is expressed in terms that are reducible, by an ultimate analysis, to equal units of linear extension (§ 27), which were originally fixed by the direct apposition of like natural objects.∗ And the undeveloped sciences, consisting as yet of qualitative prevision, depending for their advance, as they do, either upon experiments requiring apparatus and skilful manipulation, or upon observations involving dissection and other analogous procedures, have similarly implied a highly-developed manual dexterity. Thus, the tactual apparatus not only serves in its lower forms to establish relations between the tangible and non-tangible attributes of things; but, in its highest forms, it indirectly serves to establish relations among the non-tangible attributes themselves.

This intimate connection between the impressibilities and the activities—between the directive and executive faculties, which we have traced in the first improvements of perception and locomotion, which we have seen exemplified in various creatures distinguished alike by their high intelligence and their developed organs of manipulation, and which we find to hold even with the human race—this mutual dependence of the cognitive and operative powers, which Anaxagoras had a glimpse of when he uttered his hyperbolical saying that animals would have been men had they had hands; is a relation yet more remarkably and more conclusively exemplified, in the reciprocity of aid exhibited by the Sciences and Arts. Strange as the proposition will at first sight seem, it needs but a little analysis to show, that the Sciences and Arts, when regarded subjectively, severally represent what in inferior creatures we call sensory and motor processes. The perceptions gained through the sensory organs and the actions performed by the motor ones, respectively become, under their most complex forms, scientific generalizations and manufacturing operations. A comparison of the extremes does not very obviously display this; but on looking at the transitions the filiation becomes manifest. It cannot be denied that the two attributes of irritability and contractility, possessed by all but the very lowest animal types, are the respective bases of the sensitive and motive faculties—that the senses exhibit subdivisions of the one, and the muscles specializations of the other. It cannot be denied that the increasingly complex perceptions to which each sense becomes the medium, together with the still more complex perceptions achieved by the union of several senses, are forms of the organism's impressibility; nor that the successive complications of motive, locomotive, and manipulative powers, are forms of the organism's activity. It cannot be denied that out of these more complex perceptions, woven into still more extensive combinations, finally arise the previsions of science; nor that all handicrafts, and after them the higher processes of production, have grown out of that manual dexterity in which the elaboration of the motor faculty terminates. And thus it cannot be denied, that sensation and the sequent motion are the prototypes of Science and Art. If, looking at the entire range of phenomena under their most general aspect, we consider the fundamental nature of the changes by which an organism adjusts itself to the environment; if we divide these changes, as we must, into those which external objects impress upon it, and those by which it appropriately modifies its relations to the external objects; if we name these respectively, the directive changes and the executive changes; we clearly see, that sensations, perceptions, conceptions, generalizations, and all forms of cognition, come under the one; while contractions, locomotions, and all kinds of operations, come under the other; and that Science and Art, so far as they are separable at all, belong, the one to the first division, and the other to the last.

This truth being duly recognized, we shall at once see the significance of the fact, that throughout the course of human progress, there has been a reciprocity of services between the Sciences and Arts like that which we have traced out between the impressibilities and activities—a continuation of the same mutual dependence. History presents no generalization more certain, than that each great step towards a knowledge of the laws of things, has facilitated men's operations on things; while each more successful operation, has, by its results, facilitated the discovery of further laws. Astronomy and agriculture; geometry and the laying out of buildings; mechanics and the weighing of commodities; were among the earliest relations of the two. Presently, geometry, as developed by artificers, acted upon astronomy; and astronomy reacted to the great advancement of geometry. Through the medium of the scales, mechanics, joined with the science of number, influenced the metallurgic arts, gave definite alloys, introduced metallic instruments; and by so doing, both advanced the accuracy of astronomical and other observations, and improved all those processes of production for which metallic tools are employed. Metallurgy too, by supplying plane and concave mirrors, initiated optics; and the first proposition in harmonics was reached by the strings and weights which the arts furnished. Not to trace out this reciprocity in detail, it requires only to look at its modern manifestations, in the dependence of navigation on astronomy, magnetism, and meteorology; and the aid rendered to magnetic and meteorologic science by navigation—in the development of geology by mining, quarrying, and well-sinking; and the guidance which geology now gives in the search for coal, metals, and water—it requires but to observe how the definite compounds and elements with which chemistry deals, were at first brought to light by the arts; and that the arts are now all more or less dependent on chemistry—it requires simply to consider that there is scarcely a single observation at present made in science, but what involves the use of sundry instruments, supplied by the arts; and scarcely a single art-process but what involves some of the previsions of science—it requires but to glance at these relations, to perceive, not only that the reciprocity exists, but that it has been ever becoming more active. And this last fact yet further elucidates the general truth we are contemplating. For, as we found when tracing upwards the directive and executive faculties, that in their higher developments they become more and more mutually dependent—that the completer forms of visual and tactual perception are impossible without complex muscular adjustments, and that the more elaborate actions require the constant overseeing of the senses; so, we now find that in the development of these still higher cognitive and operative processes, the advance is towards a reciprocity so active that each further cognition implies elaborate operative aid, and each new operation implies sundry elaborate cognitions.

Still more clearly will these correlations be perceived, on regarding them under their concrete aspect. From our present point of view we may properly say, that in its higher forms, the correspondence between the organism and its environment, is effected by means of supplementary senses and supplementary limbs. Whether a man crushes an object with his hand, with his teeth, with a vice, or with a hydraulic press, matters not in so far as the relation between the stimulus and the action are concerned; nor does it affect the fundamental nature of the perception, whether the relative lengths of two lines are determined by simple inspection, or by placing them side by side, or by means of a pair of compasses. Thus, all observing instruments, all weights, measures, scales, micrometers, verniers, microscopes, thermometers, barometers, &c., are artificial extensions of the senses; and all levers, screws, hammers, wedges, wheels, lathes, &c., are artificial extensions of the limbs. The magnifying glass adds but another lense to the lenses existing in the eye. The crowbar is but one more lever attached to the series of levers forming the arm and hand. And the relationship which is so obvious in these first steps, must hold throughout. This admitted, and the reciprocity which we have traced between the higher cognitive and operative processes, will be yet more distinctly seen between their respective organs. The development of these supplementary senses, is dependent upon the development of these supplementary limbs; and vice versâ. Accurate measuring instruments, presuppose accurate instruments for turning and planing; and these cannot be made without the aid of previous measuring instruments of some accuracy. A first-rate astronomical quadrant can be produced only by a first-rate dividing engine; a first-rate dividing engine can be produced only by first-rate lathes and cutting tools; and so, tracing the requirements backwards, it becomes obvious that only by often repeated actions and reactions upon each other, can either directive or executive implements be brought to perfection. Only by means of artificial limbs can artificial senses be developed; and only through artificial senses does it become possible to improve artificial limbs.

These truths—this affiliation of the Sciences and Arts upon the lower forms of cognition and action; and this mutual dependence of the Sciences and Arts, whether considered in their respective processes or the agencies by which those processes are achieved—throw back a strong light upon the primitive connection of the impressibilities and activities. That reciprocity which we found to exist between these in their simpler forms, is a reciprocity which becomes yet more certain on discovering that it holds between those highest manifestations of the directive and executive powers displayed in human progression. When, after seeing how multiplied motions must produce multiplied sensations, and conversely—when after tracing up the like relation between increasingly specialized perceptions and increasingly specialized actions, we find it to obtain between these most complex cognitions and those most complex operations which we term Science and Art—and when we see, not only that these have developed together, but, by tracing their actions and reactions upon each other, also see that neither could have advanced separately—when we see all this, it becomes an irresistible conclusion, that there exists throughout, that mutual dependence which analysis and induction indicate. It becomes an irresistible conclusion, that as discoveries in Science have improved the Arts, and improvements in the Arts facilitated discoveries in Science; so, from the beginning, each more developed impressibility has aided the activities, and each advance in the activities has opened the way to higher impressibilities.

Returning now from this long but needful digression, to our immediate topic—the increase of the correspondence in complexity—we perceive how, as was alleged, the two divisions of it simultaneously pass through parallel phases. Starting from the production of a single contraction by a single irritation, and step by step ascending to more heterogeneous motions and more heterogeneous stimuli; we find, in all stages, a more or less constant ratio preserved. Indeed, we may almost say, that, à priori, a complex operation is impossible without a complex cognition to guide it; while, conversely, a complex cognition is impossible without the experiences derived from complex operations: and so we may argue, that this duplexity in the progress is necessary. Moreover, it may be remarked, that not only do the directive and executive elements of the correspondence, develope hand in hand; but the kinds of complication they eventually assume are of analogous characters. That union of generalities with specialities which we found to distinguish the highly elaborated cognitions of Science, is visible also in the highly elaborated operations of Art. Just as a particular conclusion in Science, is reached by applying to special data a general principle, which general principle applied to other data, gives other conclusions; so, a particular product of Art, is obtained by subjecting to special manipulations, the results of some more general process, which results of some more general process, subjected to other manipulations, yield other art-products. And thus the parallel holds, not only between the degrees of these mutually-dependent complexities, but also between their kinds.

§ 157. That this increase of the correspondence in complexity, exhibited in the ascending developments of Life in general, has continued throughout human civilization, we have incidentally seen in the course of the above argument. The gradual evolution of Science and Art, just traced out with another aim, so abundantly exemplifies this, as to render further exposition unnecessary. There is, however, one aspect of this progress which it may be well to notice; namely—the advance that has taken place, not simply in the complexity of the cognitions and operations that have been age by age attained to, but in the ability to receive complex cognitions and perform complex operations.

For it is not, as most suppose, that scientific and artistic progress, is due simply to the accumulation of knowledge and of appliances; but it is that the impressibilities and activities have themselves grown to a higher complication. There is distinct evidence from various quarters, that the minds of the inferior human races, cannot respond to relations of even moderate complexity; much less to those highly complex relations with which advanced science deals. According to the traveller, Lieutenant Walpole, it is remarked of the Sandwich islanders, by their teachers, “that in all the early parts of their education, they are exceedingly quick, but not in the higher branches; that they have excellent memories, and learn by rote with wonderful rapidity, but will not exercise their thinking faculties.” That is to say, they can readily receive simple ideas, but not complex ones. Again, it is asserted of the Australians, that “some of them are very quick at acquiring knowledge, but they have no power of combination or concentration.”∗ The reports of Hindoo schools, disclose, though in a less marked manner, the same fact. And according to Mr. W. Chambers, one of the reasons assigned by the Americans for not educating negro children along with white children, is, that after a certain age they “do not correspondingly advance in learning—their intellects being apparently incapable of being cultured beyond a particular point:” an allegation, which, though liable to the suspicion of partisan bias, so far accords with the independent statements previously quoted, as doubtless to have some basis. In all these cases, as also in the minor cases continually occurring among ourselves of inability to understand subjects and reasonings passing a certain order of abstruseness, the true interpretation is, that the cognitive faculties have not reached a complexity equal to the complexity of the relations to be perceived. Moreover, it is not only with purely intellectual cognitions that this holds; it holds also with what we distinguish as moral cognitions. In the Australian language there are no words answering to justice, sin, guilt. Among various of the lower races, acts of generosity or mercy are utterly incomprehensible. That is to say, the more complex relations of human action in its social bearings, are not cognizable. And thus, the large-brained European differs from the small-brained savage, not simply in the complexity of his manifestations, intellectual and moral; but these have been step by step made possible by successive complications of faculty.

Having, in the previous chapter, pointed out how greater length and higher degree of life, accompany increased speciality and increased generality of correspondences; it needs not to dwell on the fact that where both these unite in producing correspondences of increased complexity, the like result must happen. All that requires just indicating, is, that not only is this true of those more and more complex cognitions, which, through the medium of Science, advance the Arts; but it is true of those more complex moral cognitions, which, by making social order possible, contribute to that greater individual safety which social order brings.

[∗]For explanation, see the before-mentioned essay on “The Genesis of Science.”

[∗]See Proceedings of the Ethnological Society.