But it may be said that mind is but a kind of neural function, and that physiological psychology will give us the true key to consciousness. But if one has never known any psychosis, as fear, directly in himself and indirectly in others, how will he find it in any nerve activities? Nervous activities are significant of psychosis only so far as psychosis is already known. In fact, the sciences of neurosis and psychosis are radically distinct. I stick a pin in my finger, the facts of pain, volition, anger, etc., are of one order knowable only by introspection, the nerve excitation, current and reaction are of another order, constitute a complete circle, and are known only by inspection. Neurology in its own field can afford to ignore psychosis, for it does not find it: it finds only neural changes, and psychology likewise can afford to ignore physiology. These sciences stand self-sufficient, and may develop indefinitely each in its own way without meeting. Divide and conquer. The present mingling of the two is greatly to be deplored. Thus in current books we often find such sentences as this: “The prevalent view hitherto has probably been that the same nervous apparatus which on moderate excitement produces sensations of pressure or temperature, produces feelings of pain when irritated with increased intensity.” (Ladd, Outlines Physiological Psychology, p. 387.)

This confusing of objective and subjective terms, sensation and irritation, is but too frequent in recent treatises. There is no way yet found of discovering psychic facts in neural, or neural in psychic, whatever may be their connection and interdependence. If we must have a cross-interpretation, the psychologist has the vantage-ground on the basis of evolution by struggle. Nisus has developed all sense and motor organs and all nervous organs. It is the effort at seeing that has produced the optic nerve and the physiological function of sight. The vision and visual organ of the eagle came by incessant looking for prey during thousands of years. Hence mind is not reflex or concomitant of nerve, but nerve is outgrowth of mind in the struggle of existence, and a psychological physiology is better than a physiological psychology.

The psychological field is then first, self; second, other selves or individuals. In this latter phase of human psychology we have the psychology of adults, then adolescent, senile, infantile, sexual, and racial psychology. In sub-human or comparative psychology we include animals, wild and tame, also all discussion on plant psychism, mind stuff (e.g. Clifford’s), etc. In superhuman psychology we include all doctrine of cosmic intelligence, teleology (vide Mind, x. 420).

We have limited ourselves to evolutionary psychology and that of the feelings, and our data are mostly from adult human consciousness. Evolutionary psychology bases itself on the idea that mental development originates and is continued through struggle or will effort. Such evidence as we can gather points to feeling, impelled exertion as the essence of psychic evolution, and it proves fruitful when assumed as a guiding principle. And the principle of struggle is final. We cannot admit with Bain a principle of spontaneity. The activities of a new-born lamb are seemingly spontaneous only because they are the results of energies stored in ages of psychic effort. This doctrine of struggle does away with all impressionism and all passivity theories. Mind is not a receptivity, an association of impressions, a reflex or concomitant of physiological activities, but it is dynamic determining vital fact, an active response to the conditions of self-existence. This impetus of struggle and striving seems to feed all life and make life, and has its place, perhaps the highest in the dynamic whole we term the universe. While the significance of struggle is a question for philosophy, yet, as matter of fact, it is the only method of realization we know; and the office of humanity is the providing a wider and higher scope for struggle, the making new and independent life regions. Science and art, ethics and religion, which are at bottom only phases of emotionalism, are with utmost toil developed for themselves, and new emotions now arising and yet to arise will be cherished for their own sakes. Mind begins and continues long as the servant of the body, it ends by making the body its servant, the instrument of the spiritual life, the temple of the Holy Ghost; but all its evolution is through supreme effort. In the spiritual evolution he who loveth his life shall lose it, he whose struggle is in the primitive stage, namely, for material existence, loses thereby the real life, the life of the spirit.

It is possible, indeed, that we may over-estimate this salient fact of struggle, and certainly, in the present state of psychology, modesty is most commendable. We would be far from assuming that the horizon of our mind is the limit of the universe. However, assuming mind as a biological function continually evolving in the service of self-conservation and self-furtherance, our endeavour has been to point out the general trend of the evolution of feeling, and to analyze some of its more important features. The little exploration we have made suggests the greatness of the unexplored field of mind, the vast number of psychoses unknown, and perhaps unknowable. The difficulties of the subjective method make it seem almost impossible to trace a complete history of mind. For mind to return over and realize its whole growth in all its ramifications seems quite as hard as to develop new forms, or a whole region of artificial psychosis. In the filling up of missing links, psychology presents vastly greater difficulties than biology because of its subjectivity of method and the evanescent nature of the facts. Further, the more I analyze consciousness, the more I am convinced of the great and often unexpected complexity of apparently simple forms, and I am satisfied then the simplicity and completeness of the system-making psychologists, physiological or idealistic, is factitious and delusive. An inductive science of mind is yet in its infancy. My conclusion that mind was at first, and is always as progressive, feeling-impelled will, and that sensing arose as secondary, as useful cognitive effort, is simply the best reading I can make from present data when assuming the current doctrine of evolution.

A very important point, which needs to be worked out more fully than we have been able to do, is as to the nature of revival as involving emotion. Sense of re-experience and of the experienceable is one of the most important acquisitions of mind. The self-consolidation and organization of experience certainly does not come in the first place by any mechanical association, but we must assume that all mental progress is the result of the most intense, though often blind and fortuitous striving. But just how the return of an experience is cognized as return and as experience, and so becoming basis for emotion, this is a most difficult inquiry on which we have made but a few remarks in the chapter on the nature of emotion. Just when and how sense of experience is generated, and what is a full analysis of its nature, must be postponed to some future study, but I am convinced that a very fruitful field for investigation lies in this direction. Experience certainly does at a very early stage become compound, become self-appreciative in some form, as sense of the potentiality of things, but the elucidation of progress in this line is confronted by many difficulties. The history of ideation or representation as a power for self-conservation has yet to be traced with definiteness and completeness.

Another point, which needs a far fuller discussion than we can now give, is as to the nature of organic interaction in consciousness, as to the real quality of psychic cause and effect. We have all along assumed feeling as stimulant of will, both the will to know and the will to act, but just how does feeling develop will as struggling effort? What is the exact mode of connection? We conceive readily of physical impact as determining effects in the material world, and we conceive a transference and transmutation of energy, but in the psychic realm we have no entities as permanent existences susceptible of entering into relation with other entities. How then does a pain incite a will activity? A peculiar form of consciousness we term will activity does directly follow upon feeling pain, and, within limits, the greater the pain, the greater the willing, but we have no theory to express the mode of connection of these consciousnesses. All that we can say is that one does follow upon the other as somehow caused by it. Yet it is certain that the limitation of conscious capacity must in every individual determine a definite range of interaction, and, beyond some particular point, the more I feel, the less I will, and vice versâ. But the phenomenon of interference is likewise as obscure as that of excitation. The development of distinct organic forms of consciousness is slowly carried forward, and they exercise a definite dynamic relation to each other, though the mode is as yet wholly obscure. Thus the largest subdivisions of consciousness, knowing, feeling, and willing, become determined as distinct organically related modes, like the nervous, nutritive-circulatory and motor systems forming one organic whole body. These psychic modes attain gradually an intricate and definite development, whose constant interdependent connection with an individual body we term a “mind.” And we must remark that this vital relation of one consciousness and one form of consciousness to another is in no wise effected through apperception, through a third distinct consciousness, a cognitive one, which unites them in idea. A feeling excited a will act long before there was consciousness of either, or of their relation. In general we must say that consciousness does not consciously forge for itself its own relations, but that in by far the larger part of psychic development new modes of consciousness and their inter-relations come in a totally unforeseen way, by a blind striving in the struggle for existence. It may be doubted, indeed, if even the most advanced human mind can really invent a new consciousness or a new relation in consciousness, but by intense effort it attains them. One of the obscurest points in biology is as to the nature and cause of morphological variation, and the subject of mental variation is for psychological science far more obscure. We presuppose that mental variations somehow arise in response to sudden and great emergencies, and in connection with the severest effort. Mental progress is, in all the earlier life at least, only achieved under pressure of intense pain actually experienced or ideally so,—emotion—and in some way an appropriate and saving psychosis as response of organism to environment originates. This new form may be indistinct, and proceed as a gradual differentiation from previous types, still the method of action of the motive force seems mysterious. We can see, indeed, the advantage which accrues, for example, to the animal which is first able to detect danger or nutriment by scent, but just the method of the rise and progress of scenting as a conscious process seems difficult to trace. We cannot say that power of smell arose because organs of smell were developed; this puts the cart before the horse. It is the struggle to sense that is the prime motive force in developing the sense organs and not vice versâ. We do not smell because we have noses, but we have noses because we smell. That the sense of smell is a differentiated general sensation is likely enough, but we are unable to follow the steps. We know that the higher development of our present senses is attained only through great exertion, which determines a physical basis and organic progress—as in microscopy, telescopy, and so-called mind-reading—and if humanity is to develop in the future an electric sense or a telepathic sense, it must be reached by the intense struggle of a very few. We must believe that every mode of mind is at bottom but some modification of pre-existing forms, and it may be that as all modes of the material are interpretable in motion, so the manifold mental may be equally resolvable into some one type. Yet so far as we can now see, feeling, will, and cognition seem radically and primitively distinct. The missing links in mental evolution are most difficult to determine, for, as we have often remarked, while we can with comparative ease both determine fossil organic forms a priori and discover as realities, the intermediate mental forms can only be known through a subjective realization.

It does not help us to ascribe the advantageous variation to chance, a word, indeed, which does not belong to the dictionary of science, for it is but a cover to ignorance. Chance means that the determinate line of causes is hidden from the observer, who only knows that one of several results will take place. Chance is thus wholly relative; the gambling of savages is often calculable to the European, and so every affair of chance, as dice throwing, might be calculable to a superior intelligence who could compute or watch every turn of the dice. Chance, then, does not reside in the outward thing, is not a property of phenomena, but is wholly a subjective limitation of the investigating mind, hence to ascribe variation, physical or psychical, to chance is simply to objectivise our own imperfect cognition. The pre-supposition of all science is that every event or change has its definite determining antecedents, and that these are cognizable; hence the doctrine of chance has no place in any complete and real science of phenomena. That organism is, indeed, fortunate, which first achieves some notable and valuable psychic mode, but this good fortune does not in any wise come by chance, or by the passive enjoyment of concurrent favourable circumstances, but it is a well-earned superiority attained only by the severest and most patient responsive struggle, and there in every case a determinate series of steps in mental process which may ultimately be traceable.

Mental forms also arise through perversion, competitors perverting originally advantageous variations, as has been already pointed out for paralysing-fear, sense-destroying anger, etc. Atavistic tendency gives pseudo-variations. Certain mental forms may be negative in origin, that is, merely reactionary from previous states. Given a high degree of any joyous emotion, say hope, and suddenly remove its conditions, and the swing is back beyond the zero point of emotion to actual negative emotion, as despair. Still the whole gamut from positive to negative, as from highest hope to deepest despair, is but a single generic emotion form of polar correlate elements, which have equally developed through struggle.

The subject of psychic intensity in general, and feeling intensity in particular, is likewise obscure and difficult. Physical intensity is comparatively easy to investigate in its nature and laws. For instance, in the case of light we clearly conceive its nature in terms of molecular motion, we measure it exactly by photometers, and we know it to proceed by the law of inverse squares. We have no similar certainty and clearness with regard to mental intensity. We speak of suffering very slight or very intense pains, but there is no scientific theory or valuation of psychic intensity. Mere physical intensity does not explain psychic, and we know that variations in rapidity of ether waves, for example, give, not quantitative, but qualitative psychic variations. 640 billion vibrations are felt subjectively as the comparatively feeble colour blue, while 450 billion gives the striking and intense colour, red. It is only within a certain range and with certain forms of forces that Weber’s law of geometric and arithmetic increase applies.