extremes of the evolution this consensus among the various orders of correspondence is clearly traceable; but the further the development advances the more intimate does the consensus become. If we consider the results of improved vision in some inferior species, we s<3e that besides bringing within view a wider region, and so extending the correspondence in Space, and besides giving earlier notice of approaching prey or enemies, and so extending the correspondence in Time; it brings a greater power of discriminating among near objects, and so initiates correspondences of higher speciality. Similarly, on observing what takes pla^e in the man of science who adjusts a further inner THE CORRESPONDENCES IN THEIR TOTALITY. 887 relation to some further outer relation — say tlie relation between an electric current and the magnetization of iron — we see that while the discovery is an advance in speciality of correspondence, it immediately leads to a variety of advances in all orders of correspondences. It makes possible generalities and specialities of correspondence to the phenomena of terrestrial magnetism. Through the galvanometer it leads to adjustments, both general and special, between inner relations and the outer relations subsisting among electrical phenomena of various orders.. In the same way it does the same thing in respect to an immense range of chemical phenomena. And it similarly brings within reach a vast series of thermal phenomena.
Through the agency of the electric telegraph which has also grown out of it, it makes possible hosts of special correspondences between men's actions and the changes occurring at remote points on the Earth's surface j it enables astronomers to ascertain the relative longitudes of observatories with the greatest nicety; and by supplying them with an improved means of registering meridional transits, it gives better data for calculating the distances and motions of the stars, for determining the structure of our Sidereal System, for ascertaining the motion of the Sun through space. In such among other ways has this one advance facilitated other advances of all orders and in all directions; and, in a greater or less degree, the like happens from every advance.
So that from the lowest to the highest forms of life, the j increasing adjustment of inner to outer relations is one \ indivisible progression. Just as out of the homogeneous j tissue with which every organism commences, there arises by continuous differentiation and integration, a congeries qf organs performing separate functions but remaining mutually dependent, or rather growing more mutually dependent; so, the correspondence between the actions going on inside of the organism and those going on outside of it, beginning with some simple homogeneous correspondence, gradually becomes differentiated into various orders of correspondences, which, though constantly more and more subdivided, maintain a reciprocity of aid that grows ever greater. These two progressions are in truth parts of the same progression. Without dwelling on the fact that the primordial tissue displays the several forms of irritability in which the senses originate, and that the organs of sense, like all other organs, arise by differentiation of this primordial tissue — without dwelling on the fact that the impressions received by these senses form the raw materials of intelligence, which.arises by combination of them and must therefore conform to their law of development — without dwelling on the fact that intelligence advances pari passu with the advance of the nervous system, and that the nervous system has the same law of development as the other systems— without dwelling on these facts, it is sufficiently manifest that as the progress of organization and the progress of correspondence between the organism and its environment, are but different aspects of the evolution of Life in.general, they cannot fail to harmonize. In this organization of experiences which constitutes evolving Intelligence, there must be that same continuity, that same sub-division of function, that same mutual dependence, and that same everadvancing consensus, which characterize the physical organization.
§ 174. That Intelligence has neither distinct grades nor is constituted of faculties that are truly independent, but that iteju^e^ are the effects of a complica- *$ ^,?5?^ij.S!!!?^bi?^teps out of the simplest *?' *s?,conc*usio11 equally thrust "upon us when we 9m ^e characteristics of the organism to the characteristics of the environment. Every act of Intelligence being, in essence, an^adjustment of inner to outer relations, it results that as, In~The advance of this adjustment, the THE CORRESPONDENCES IN THEIR TOTALITY. 889 outer relations increase in number, in complexity, in heterogeneity, by degrees that cannot be marked, there can be no precise demarkations between the successive phases of Intelligence. The space through which the correspondence gradually extends, has no definite boundary up to which a certain order of mind is competent but beyond which another order is required. No exact length of time can be named as the greatest to which the actions can be adjusted by one supposed species of guiding principle. Among the specialities of external phenomena it is impossible to fix on that which can be reached, but not passed, by a particular denomination of mental endowment. Environing objects and environing actions passing as they do into higher and higher complexities by gradations that are insensible, it is impossible to draw among them, a line up to which some alleged kind of intellectual process may go but beyond which it cannot go.
Evidently then, the classifications current in our philosophies of the Mind can be but superficially true. Instinct Keason, Perception, Conception, Memory, Imagination, WJJJ^ &c., must be eitEer conventional groupings of the "correspondences, or divisions among the operations which are instrumental in effecting the correspondences. However widely contrasted they may seem, these various modes of Intelligence cannot be anything else than either particular ways in which the adjustment of inner to outer relations is achieved, or particular parts of the process of adjustment.
That there are distinctions among the groups of phenomena thus named is doubtless true. But, when^ considered in their essentials, it becomes manifest that some of them merge lotojj^^ into a trank, andjbhat the rest are but the different constituents of which some branch is made up. * § 175. Here a new region of inquiry opens before usl Having found_that all the phenomena oj come within this formula which unites tliem with tliose of J Physiology, we have now to see what distinguishes the one f £roup from the ot¥er." We decided that we should "best I Mnl the requirements of clear exposition by first exhibiting I mental evolution as it may be most generally conceived,, ' and subsequently specializing the conception" (§ 130). One of these steps has been taken in the preceding chapters, which have presented psychological truths under their broadest aspect as biological truths. It remains to take the other step by presenting psychological truths under their differential aspect.
For, as was pointed out in §§ 54, 55, though objective Psychology, as dealing with a certain order of vital activities, comes within Biology^, considered as the entire science of Life, it nevertheless constitutes a sub-science clearly marked off from the rest; just in the same way that Chemistry, although a part of the general science of Molecular Physics, is rightly erected into a separate sub-science, because it deals with the re-distributions of heterogeneous molecules instead of the re-distributions of homogeneous molecules.
That which distinguishes the science of psychical life from the science of physical life, we found to be the distinct cognizance which it takes of phenomena outside the organism as well as of phenomena inside the organism. We saw that, passing beyond the question with which FbjSlfis deals — What is the connexion between two phenomena A and B in the environment? and passing beyond the question with which Physiology deals — What is the connexion between two changes a and b in the organism? the question with which Psvjdiologjr deals is — What is the connexion between these two connexions? How is the relation a to 6 in the organism adjusted to the relation A to B in the environment? While admitting, or rather asserting, that Biology at large tacitly recognizes phenomena in the environment as implied by phenomena in the organism, I pointed out that the THE CORRESPONDENCES IN THE IE TOTALITY.
recognition is but tacit,, and that the great mass of biological inquiries are carried on without reference to it; whereas in Psychology the recognition of environing actions and relations is avowed and all-essential — is repeated from moment to moment — is a necessary component of every proposition. The distinction then drawn in the most general way,, has recently been illustrated in various special ways. For while, that we might obtain the most comprehensive conception of psychological phenomena, we returned to the most general point of view, and have throughout the foregoing chapters looked at them simply as vital phenomena coming within the definition of Life as a whole; we have met with abundant proof that the truths of Psychology differ from the truths of Physiology by taking for their subject-matter neither the relations of inner acts nor the relations of outer acts, but the adjustments of the inner to the outer. On glancing backf oveFlnese chapters it will be found that in the first two of them, treating of purely physical life as exemplified in pb^nts^and in^animals of the very lowest types, the environment was recognized in the smallest possible degree: only that part of It which touched the organism had to be taken into account. But the moment we rose to a type of creature which adjusts certain organic relations to relations of which both terms are not presented to its surface, we passed into adjustments of the psychological order.
As soon as there exists a rudimentary eye capable of receiving an impression from a moving object about to strike the organism, and so rendering it possible for the organism to make some adapted movement, there is shown the dawn of actions we distinguish as intelligent. As soon as the organism, feebly sensitive to a jar or vibration propagated through its medium, contracts itself so as to be in less danger from the adjacent source of disturbance, we percerfe a nascent form of the life classed as psjchicaL That is say, whenever the correspondences exhibit some extensio_, in Space or in Time, some increase of Speciality or Con/ Iplexity, we find we have crossed the boundary between {physical life and psychical life. In so far as it deals at all Hvith the adjustments of inner actions to outer actions, Physiology limits itself to the few in which the outer actions are those of agents in actual contact with the or-- ganism — food, aerated medium, and things which produce certain effects by touch (as insects which fertilize flowers); thus leaving to Psychology all other adjustments of inner to outer actions. So that, practically, the spheres of the two are as clearly divided as the organism is divided from its environment by its limiting membrane.
§ 176. Quite apart, however, from the considerations thus recalled and enforced, we_j^ee_Jhere the need for a more specific and definite interpretation of that mental evolution which jbhe preceding chapters exhibit in its fundamental form. The presentation of Intelligence as an adjustment of inner to outer relations that gradually extends in Space and Time, that becomes increasingly special and complex, and that has its elements ever more precisely co-ordinated and more completely integrated, leaves us with a conception which obviously requires further development. ffhe various^ degrees and modes of Intelligence known as Instinct, Memory, Season, Emotion, WiU, and..the rest,?mustjbejbranslated in terms of this conception. If, as above alleged, the several grades of Mind and its component faculties, are phases of the correspondence and factors in the correspondence, they can be interpreted as such; and to complete the argument it is needful that they should be so interpreted, We have now, then, to enter upon another department of our subject. Closing here the General Synthesis, and carrying with us the fundamental truth evolved by it, it remains to found upon that fundamental truth a Special Synthesis.
PAET IV.
CHAPTER I.
THE NATURE OF INTELLIGENCE.* § 177. The two great classes of vital actions called Physio-:' logy and Psychology are broadly distinguished in this, that while the one includes both simultaneous and successive1 changes the Q.ther_includes successive changes only. The-5 phenomena forming the subject-matter of Physiology present themselves as an immense number of different series bound up together. Those forming the subject-matter of Psychology present themselves as but a single series. A glance at the many continuous actions constituting the life of the body at large, shows that they are synchronous — that digestion, circulation, respiration, excretion, secretion, &c., in all their many sub -divisions, are going on at one time in mutual de-.,, pendence. And the briefest introspection makes it clear that| the actions constituting^^^u^t occur, not together, but one! after another. -— —•* jS"o impassable chasm between them is thus constituted however. Even were the highest psychical life absolutely distinguished from physical life in the way alleged, which we * This chapter and all its successors composing Part IV., remain in substance the same as in the original edition. The numerous changes d? expression, omissions of superfluous passages, and occasional additions of explanatory sentences, have been such only as conduce to the clearer presentation of the doctrines set forth — the doctrines themselves being unchanged. I name this for a reason sufficiently indicated in the preface.
stall presently see reason to doubt, it would still be true that psychical life in its lower phases is not thus distinguished: the distinction arises only in the course of vital progression. That gradual differentiation and integration, I seen alike in the evolution of organic structures and in the ' evolution of the correspondence between their actions and actions in the environment, is also seen in the separation of this correspondence into its two great orders. "While through \ it have resulted the various subordinate divisions of the 1 correspondence, through it also has resulted this funda- I mental division. We will look at a few of the facts.
> Passing over the small animals moved by cilia, in which the independence of the many irritations and motions simul-1 taneously going on is manifest — passing over the Zoophytes, l in which moderate local stimulations produce local contrac- \ tions without affecting the organism as a whole — passing "| over these creatures devoid of nervous systems, let us con- *j. sider what happens when the nervous system has attained ^ some development. In such so-called Badiata as ] the Star-fish, each of the several like divisions composing the 4 body " is connected with a ganglionic centre, that seems to be subservient to the functions of its own division alone, and I to have little communication with, or dependence upon, the ') remainder /'* The result is that what elementary psychical J changes the creature manifests, take place simultaneously in ; different parts of its body: each part separately responding ;; to the impressions made on it. And hence the fact that J for a length of time after being divided from one another, f> the rays severally continue to exhibit their ordinary i actions. In the Articulata, specially fitted by their structure for showing it, this 'dispersion of the psychical life is well brought out by experiment. " The Mantis religiosa j Customarily places itself in a curious position, especially when i ' * Carpenter's Principles of Comparative Physiology. Fourth edition, THE NATURE OF INTELLIGENCE. 397 threatened or attacked, resting upon its two posterior pairs of legs, and elevating its thorax with the anterior pair, which are armed with powerful claws: now if the anterior segment of the thorax, with its attached members, be removed, the posterior part of the body will still remain balanced upon the four legs which belong to it, resisting any attempts to overthrow it, recovering its position when disturbed, and performing the same agitated movements of the wings and elytra as when the unmutilated insect is irritated; on the other hand, the detached portion of the thorax, which contains a ganglion, will, when separated froui the head, set in motion its long arms, and impress their hooks on the fingers which hold it. — If the head of a Centipede be cut-off, whilst it is in motion, the body will continue to move onwards by the action of the legs; and the same will take place in the separate parts, if the body be divided into several distinct portions.* * * * If the body be opposed in its progress by an obstacle of not more than half of its own height, it mounts over it, and moves directly onwards, as in its natural state; but if the obstacle be equal to its own height, its progress is arrested, and the cut extremity of the body remains forced up against the opposing substance, the legs still continuing to move."* All which facts imply that even in animals of this comparatively-advanced organization, both orders of vital changes are simultaneous and successive: the differentiation of the psychical from the physical life is but slight. Even among Vertebrata of high ^ types, this | differentiation is by no "means complete. Many of the actions! are partly voluntary, partly automatic; and may be performed j with various degrees of consciousness, or without conscious- J ness. This is implied by the fact that sensations can be received, an^(^qmppui^moY§ments performed, inJ/Ee.,.absence °^ Mi£jgreat ^^Q113 cefi^res • -^SESEiSSi® on frog§ yield clear proof that actions of cpnsiderable * Carpenter's Principles of Comparative Physiology, p. 665.
may be efficiently executed without the aid of the brain (§ 22). The vivisections of Longet, Vulpian, and others, show that mammals continue to feel and retain certain of their locomotive powers, when both cerebrum and cerebellum have been r£moj;ed; and'l;hari)7rQls similarly deprived of these great cephalic ganglia can still walk about, fly, and even pick up food. Nay, there are cases on record of infantp that have for days continued to breathe, cry, suck, and go through various movements, although born without either cerebrum or cere-„ bellumv *"* Apart from evidence of this kind, the per- I sonal experiences of every adult demonstrate to him that I there are many actions belonging to the psychical division, I which either may or may not enter into the mental current. The motion of the legs is necessarily accompanied by various muscular and tactual changes. These, together with the state we call volition, may be distinctly present to consciousness— may be thought of as by a child learning to walk; or they may, as in ^ordinary walking, be left almost wholly out of consciousness. The processes we perform whjle^jeatmg display a similar relation. The several acts by which each morsel is selected, cut, prepared, and carried to the mouth, may perhaps be held to enter into the current ^ of our thoughts; though in general, and especially during ^conversation, they obtrude themselves on consciousness | very slightly. But many of the^ impressions and mpjbions involved, are next,to uncon^ouZ The^tactual feelings which the knife-handle gives, the contractions by which it is grasped, and the muscular changes which the arms are every moment undergoing, scarcely at all occupy the attention, ^^ftj^at 9Sij^^ or quasipsychical actions going on in the organism.
thread of consciousness; while t£er6ihers form one or more~3Is5n as it were, occasionally inosculate with the thread of consciousness.* * I find that there may sometimes he detected as many as five simultaneous series of nervous changes, which in various degrees rise into conscious- THE NATURE OF INTELLIGENCE. 399 So thafc only by gradual differentiation have the actions constituting psychical life become specially successive, instead of simultaneous and successive; and the distinction is not even now complete. In the lowest types each part of the organism, while it performs by and for itself all other vital functions, also responds by and for itself to external stimuli; and the psychical changes,, or what foreshadow them, are both simultaneous and successive to as great an extent as the physical changes. When a nervous system makes its appearance, these incipiently-psychical changes become slightly co-ordinated — have their various strands connected. As the nervous system develops and integrates, the twisting of these various strands of changes into one thread of changes grows more decided. J3ut to the last their union remains imperfect. The vital actions constituting the subject-matter of Psychology, while distinguished from other vital actions by their tendency to assume the form of a single series, never absolutely attain that form.
§ 178. This distinction between the psychical and thej physical life will be most clearlj understood, if weTconsiderj flEFmo^in which it first appears and __ tt^Jeaddng stages of I its progress.
Throughout the homogeneous tissue of which the lowest creatnres consist, there is complete community of actions. The vital processes go on simultaneously in many place? alike. These primordial organisms, if organisms they can 8S called, exhibit no differentiations of structure or func-j ad thus th^J;w^j^^ ivisions of each, are. in th^ybejrinning. one. I • that we cannot call any of them absolutely unconscious. When walking! there is $& locomotive series; there may be, under certain circumstances, a tactual series; there is very often (in myself at least) fn auditory series, constituting some melody or fragment of a melody which1 haBB&i me; and there is the visual series: all of which, subordinate to the dominant consciousness formed by some train of reflection, af e continually ) crossing it and weaving themselves into it.
> The first great differentiation established is that between the inner and outer tissues— the substance of the body and its limiting membrane. The parts of the original protoplasm are subject to but a single contrast of conditions — that between contact with one another, and contact with the environment. The external portions are bathed by the surrounding medium; the internal portions are not. And in response to this primary unlikeness of conditions, there eventually arise unlikenesses of structure and function.
That which is permanently outermost takes on the modified form of vital action which its circumstances demand. That which is permanently innermost similarly assumes a more specialized order of activity (Prin. of Bio., § 287).
? The division of labour thus commenced may be considered as at first physiological only. In virtue of its 1 position, the surface necessarily monopolizes the duties of absorption — the taking in of water and nutriment and oxygen; while to the included mass remain such duties as its inclusion permits. And when, by involution of the I surface, a stomach is formed, the change implies a furthei i separation of duties, such that nutrition is chiefly confined • to one part of the limiting membrane and aeration to another. But the advance is not an...adran.ce in the physiological division of labour solely. It is at the same time anjadyance,.towards Jhe segaraSoii^of j>sy chical actions from.
phy sical_pnes; and is even a first s^pTJowards'' bringing psychical actions into serial order. Necessarily assuming the vital offices entailed by its externality, the skin also assumes the office of receiving all those impressions prtjch form the raw material of intelligence. The mechanical and other changes going on in the environment, can be responded to by the organism only when it is affected by tffemj and any change they work in it must be proximately experienced by its surface. The Ja^ then, being I the part immediately subject to the various HSds of exter- Jnal stimuli, necessarily becomes the part in which psychical...-...------------...- - —:"..."...^..^ftswjs^— *•*" THE ttATUBE OF INTELLIGENCE. 403 changes are originated. As contrasted with the contained! substance, it comes to be more especially concerned in that adjustment of inner to outer relations which constitutes intelligence. But now mark the implication. The changes constituting the physical life continue to go on simultaneously throughout the entire mass. Those which foreshadow the psychical life are, in an increasing degree, localized on the outside of the mass — belong to its; outside primarily and affect some other parts secondarily. Speaking generally, therefore, we may say that while the! physical changes are being everywhere initiated throughout a solid, the psychical ones, or rather those out of which | psychical ones arise, admit of being initiated only on a j surface. Hence, even by this primary differentiation the incipient psychical life comes to be distinguished from the purely physical life, by the diminished quantity of simultaneous changes it includes.
Subsequent differentiations have like natures and results.1 This sensitiveness which forms the basis of psychical lifej is"*"in ine beginning diffused uniformly over the whole surface; but it presently becomes in some degree concentratecl. Though, generally, all parts of the skin remain impressible by touch, yet certain parts, having positions which expose them to frequent tactual impressions, become more susceptible than the rest; and in these parts most of the sensations arise. That is to say, the ej)i-peripheral ch^^s^qnning^ the raw matejial,QLfetelligence, by being restricted in the area of their occurrence, have the characteristic of simultaneity further limited; and the more highly developed the tactual apparatus the more marked is the limitation.
Still greater is this limitation rendered by the eyolutipn of special senses. The olfactory and gustatorj sensatiorS are localized in smaller tracts than is the sensation of touch; and each of tnese tracts is little, if at all, capable of undergoing more than one change at a time. Yisujland D IT" auditory impressions are receivable only witHn yet narrower areas; and even the two areas susceptible of each become functionally one. The ears are simultaneously affected by the same sounds; and in the highest creatures the eyes, being so placed as to converge their axes on the samo object, yield to consciousness what seems to be one image. Nay, erac within each group of visual feelings concentration is manifest. The greatest sensitiveness of the retina is confined to a minute spot; and the feelings initiated in this spot dominate over the others in consciousness. If we add that when the most advanced intelligence is reached, the sensations arising in the nose and the palate are but occasional, while , those arising iu the eyes and ears are perpetual -, it will be seen to what extremely small portions of the organism the ; changes which form the chief raw materials of intelligence are ultimately confined.
Continued differentiation^ajQcl^integration, thus concen-• • trating* the actions out of which psychical life is evolved, first on the surface of the organism, afterwards on certain regions of that surface, afterwards on those most specialized! parts of it constituting the organs of the higher senses, and finally in minute parts of these parts, necessarily render the psychical Jife more and mot%e distinct from the physical life by * bringing its changes more and more into serial order. We have nothing to do with the progressive development of the nervous system, and the actions that are carried on throughout its mass. These internal actions are initiated by the external ones to which the senses are subject. And just in proportion as the external ones tend towards the serial form, the consequent internal ones do the same.
p § 179. This growing seriality in the psychical changes isi, "indeed, necessf&ated by advance of the correspondence. In I other words* the advance of the correspondence, the de-.hrelopment of consciousness, and the increasing /tendency THE NATURE OP INTELLIGENCE. 403 towards a linear order in the psychical changes, are different aspects of the same progression.
For how only can the constituent changes of any complex correspondence be co-ordinated? Those. abilities which an intelligent creature^ possesses, of recognising diverse external objects and of adjusting its actions to composite phenomena, of various kinds^, imply a power of combining many separate impressions. These separate impressions are received By the senses — by different parts of the body. If they go no further than the places at which they are received, they are useless. Or if only some of them are brought into relation with one another, they are useless. That an effectual- f adjustment may be made/ they must be all brought into rela- 1 tion with one another. But this implies some centre of com- f munication^commpn to them. all, through which they severally gass; and as they cannot pass through it simultaneously, they must pass through it in succession. So that as the external phenomena responded to become greater in number and more complicated in kind, the variety and rapidity of the changes to which this common centre of communication is subject must increase — there must result an unbroken series of these nervous changes, the subjective face of which is what we call a^