And this brings us again to the conception of normal function as a stable form of motion. Long-exercised function, fundamental functions of animal or plant life are forms of motion that for a very long period have found their sufficient complementary conditions in the environment, have met with but little interference in this environment. And thus we attain a conception of pleasure as that form of feeling accompanying forms of physiological motion with which there is a minimum of interference. Pleasure appears as the accompaniment of unimpaired and unimpeded function everywhere as far as our knowledge extends. Function and habit are essentially the same; habit is merely function. The functions of the species furnish the foundation of the habits of the individual, which vary according to individual surroundings and the family peculiarities acquired through peculiar circumstances. The degree of pleasure in the exercise of any function or habit bears constant relations to the strength of the acquired function, while this again bears constant relations to degree of exercise, in which the time relation plays a prominent part. Here we have, too, by implication, the explanation of the disagreeable character of the strange and new except as it corresponds to some tendency of the organism, some capability not yet exercised, in which case it appears as nothing strictly new but only as pleasing variety. From a physiological point of view, the new appears as that which demands a readjustment involving the fresh action of natural selection, and the possible destruction of the organism in case the readjustment demanded is too great. From the physical and mechanical view, the new may be regarded as a disturber of equilibrium.

To this analysis the objection may possibly be urged that obstacles often increase pleasure. If, however, a definition of obstacle be demanded, it will soon appear that what is meant by an obstacle that increases pleasure is not anything that interferes with function but rather that which is exactly its occasion and opportunity. To a man in health and vigor who sets off for a walk through the fields, a hedge or fence in the way is no real obstacle, but furnishes rather an agreeable diversion, a new method of trying his strength and getting rid of superfluous muscular secretions; it adds but the spice of some slight variety to his exercise. That which is an interruption of one function, may be the opportunity of another; and if the demands of the first function for satisfaction are not too imperative, the interruption of too great duration, the obstacle may not be felt to be disagreeable. But pain and pleasure are often mixed, since the satisfaction of one function may be the prevention of another. If, in this case, the function which is satisfied is a fundamental one, the function which is prevented a subordinate one, the pleasure exceeds the pain. If, on the other hand, the function prevented is a fundamental one, the function satisfied a merely subordinate one, the pain exceeds the pleasure.

With the ideas of unimpaired and unimpeded function as pleasurable, and of the new as demanding readjustment, we arrive at the consideration of health and disease. The free performance of any particular function is the first condition of the health of the organ of which it is the function, the regular performance of all physical functions according to the mutual adjustment of the organs of the body the condition of the health of the organism as a whole. And thus again we come round to the conception of pleasure as connected with the action that accords with the health of the organism. And this leads us to some remarks concerning the act of food-taking which may answer a possible objection to the statements made above with regard to the pleasure involved in the act. The moralist and idealist are wont to protest against any theory that may seem to give prominence to "the purely animal" side of human life. But first, we have to do, at present, merely with facts on which ethical theory may be founded, not as yet with such theory itself. Furthermore, the selection of the appetites of hunger, thirst, and sex, as illustrating the general theory of the relations of pleasure and pain to function is not made in order to lay special stress upon these appetites but because they afford, as fundamental, especially good examples. And, finally, it may be noticed that the pleasure connected with the stilling of hunger and thirst is not that of taste alone, though doubtless there are many with whom this pleasure is one of the most important of life; on the taking of sufficient and proper nourishment depends the pleasure involved in the general health of the body; the pain of non-satisfaction in this case is not simply that of a single organ but that of the whole organism. Even the deferment of a single meal beyond the usual hour often lowers the "tone" of the whole body, and the variations of too much or too little strongly influence the mood and general happiness of the individual. On the right use of nourishment depend, in great measure, the ability to cope with circumstances and the moral power of cheerfulness.

In connection with the idea of a certain equilibrium between exercise and nourishment, waste and repair, as normal, healthful, and pleasurable, Rolph's principle of the Insatiability of life may be considered. Evidently the facts of evolution demonstrate the power of the organism to advance by slow degrees beyond its original normal. But the progress is an exceedingly slow one, and the power of advance in the individual organism, at any particular point, by no means limitless, but very definitely limited. The limitations of the power of assimilation are evidenced by the evil results of over-eating, of over-satiety of function in any direction. Even at an early period of life, when growth is most marked, the capacity for assimilation is by no means limitless. The idea of insatiability is advanced by Lewes[136] in a somewhat different form. It may possibly be an aid to the comprehension of the process of growth to regard one factor, namely the organism, as the active side of the development tending to indefinite growth in all directions, and the other factor, the environment, as the regulating, resisting factor, limiting such growth; the conception may, perhaps, be legitimately resorted to as we resort to various other devices which bring into prominence some one side of a process to the neglect of others but to the simplification of our concepts and calculations. A similar device is used by Zöllner in his consideration of sun-spots.[137] But these representations should not be mistaken for actuality. The limitless expansion of the organism is as much a fiction as a theory of the limitless coercion of the environment resisted by the organism would be. The latter fiction is involved in one interpretation of the Struggle for Existence. Either view is one-sided; environment and organism both alike represent active forces, of both which combined, growth is, at each moment, the exactly conditioned resultant.

We may notice another assertion of Rolph's, namely, that growth is produced by increase of nourishment rather than that it demands[138] increase of nourishment as the Darwinians state. I do not know how the Darwinians come to be accredited with this statement in the sense which is evidently criticised by Rolph. In so far as the statement may be interpreted as meaning that growth takes place first, and without nourishment, and that the demand for nourishment then ensues on this growth, the criticism is evidently valid. But the word "demands" may be interpreted in quite a different way as designating the need of growth for its conditions, or rather (for this is the ultimate significance of the word in this sense) the logical demand of the reason, which cannot suppose anything to take place in the absence of its conditions. Any other signification of the word is contrary to the whole spirit of Darwinism, and would accord much better with a theory of Insatiability or with other forms of theory that imply a special vital principle of some sort. If, when Rolph makes the assertion that increase of nourishment produces growth, he refers, by "increase of nourishment," to the mere act of mastication, it is true that growth must be regarded as following upon this as its condition; but growth and the assimilation of nourishment are identical. And, in fact, assimilation begins in the action of the saliva in the act of mastication. Analysis of assimilation gives us sequence in one sense, since the parts of the act follow upon one another; but any interpretation which tends to draw a distinct line at any point in the physiological process, or to distinguish between assimilation as active, performed, and growth as passive, suffered, should be avoided.

We may return to the consideration of pleasure and pain as connected with function in general, with a view to a solution, if possible, of the problem of its especial connection with the will. The brain may be defined, from the point of view of the theory of evolution, as the organ of centralization through which the unity of the organism is established, and the adaptation of parts or the development of special function becomes the adaptation or function of the whole. With this physiological adaptation, an increasing breadth of knowledge by experience, the deviation of feeling from old into new channels, and the attainment of new ends of action, are associated. Just as past adaptations must have their physiological representation in brain-organization, so psychical experience is stored up to be remembered on sufficient suggestion, and finds, thus, its expression in conscious will, just as its physiological concomitants must be supposed to find their expression in nervous and muscular action. As we have seen, pleasure follows the line of evolution of function, strongest pleasure appearing in the direction of most strongly developed function, so that, just as any conflict of tendencies to function in the brain must result in conquest by the strongest tendency, the line of action must always correspond with that of the greatest pleasure. And just as the most strongly inherent function is combined with the greatest pleasure, so the representation of the performance of this most strongly inherent function is, in the conflict of tendencies before action, combined with the greatest pleasure of anticipation. This statement coincides with Stephen's remark that it is not the representation of the greatest pleasure, but the pleasantest representation, which furnishes the decisive motive to will. Contingent circumstances may introduce into the actual carrying out of the act determined upon an element of pain not before experienced, in which the wish may arise that the act had not been performed; and the strength of the tendency to action in this direction is thus diminished.

With regard to this analysis, several things are to be noted. (1) It is no more claimed that the strongest pleasure of anticipation is unmitigated pleasure than that the pleasure involved in the attainment of the end is necessarily unmitigated. Wherever there is interference, there is also pain. Where any struggle is involved, where any conflict of tendencies and wishes precedes choice, the struggle itself and the relinquishment of one or more courses in favor of the one chosen involve disagreeable elements, and the fiercer the struggle the greater the pain. Where two extremely strong tendencies thus come into collision, the pain involved may amount to agony. Our statement that the more pleasurable end or rather the one the imagination of which is the more pleasurable is the one sought by will needs therefore to be put into a somewhat different form, since, among all the methods of action open to choice in any case, there may be none the thought of which involves any positive pleasure, though there is in all or most cases some one which promises at least a negative excess of pleasure, that is, least pain. (2) No assumption is made as to the particular kind of representation or the particular kind of end with which the greatest pleasure of anticipation or of realization is combined, whether these are "higher" or "lower," sensual or intellectual, moral or immoral. It is not by any means asserted that the most moral end may not be that which is chosen. (3) It is not asserted that any direct calculation of the pleasure to self involved in any course of action necessarily contributes to choice. (4) The pleasure or pain connected with the imagination of a future event is not to be confused with the actual pleasure or pain of the event itself. The feeling experienced in the event may be wholly different from that of anticipation.

In connection with the second point, reference may be made to an assertion of Sidgwick's in his attack upon Hedonism. He writes as follows, "We have to observe that men may and do judge remote as well as immediate results to be in themselves desirable, without considering them in relation to the feelings of sentient beings."[139] The question for us here is, first, whether the emphasis of the assertion is on the word "considering,"—a question the context does not answer. It is certainly true that decisions are reached, judgments pronounced, without introspection and self-analysis, and without long reflection of any sort. It is true that, even where reflection does take place, there is not necessarily any distinct attachment of the concept "pleasurable" to results considered, whether with relation to self or to others. The dog who snatches at a piece of meat does not probably waste any time in reflecting on the pleasure he will experience in eating it; and yet we do not the less believe that if the act were not pleasurable to him he would not perform it. It may also be true that a man often pronounces results to be desirable without noting or caring for their relations to other sentient beings; but if these results are regarded by him as desirable, then they must be in some way desirable to himself, that is, must have a pleasurable relation to his own feelings. Desire appertains to sentient beings and to sentient beings as such; a thing which is desirable must be desirable to a sentient being; the desirable which is not desirable to a sentient being is the desirable which is not-desirable, a self-contradiction.

In connection with the third of the points above noticed, Rolph's assertion that not pleasure but pain is the motive to action, may be considered. The author does not mean anything else than that action is in the direction from "want," "hunger," "pain," to ends involving pleasure, so that this theory does not, when analyzed, differ fundamentally from theories which assume the motive to will to be furnished by the most pleasurable end or by the most pleasurable representation of an end. The chief point of difference is the conception of the state of consciousness preceding will as invariably one of pain, the want of the end willed as invariably painful. Now it is evident that the satisfaction of a function may be so long deferred as to involve the severest pain; hunger, thirst, may reach a degree of intensity that is frenzy, muscular inaction, in an ordinarily active individual, if long persevered in, may be combined with extreme discomfort and depression. And it is also true that all desire involves want in the sense that an end is sought because its absence is felt as undesirable. But want in this sense means merely desire, and is not necessarily combined with any real pain of deprivation. The state of consciousness preceding action may be, on the contrary, one of exhilaration, of exceeding joy of anticipation; the gratification of a desire may take place so soon after the first appearance of the desire, or the gratification of the desire become so certain so soon after the desire is first felt, that no pain of want is felt at all. Rolph, indeed, finds great difficulty in demonstrating his theory, and finally resorts to the definition of the pain which, as he asserts, furnishes the motive to action as "the pain of the absence of pleasure." He says, moreover, that not all pain is felt as such, since much feeling is below the threshold of consciousness.[140] But "unconscious pain" and "feeling below consciousness" are mere self-contradictions. Specification of that of which, as unconscious, we know nothing is a very easy way of delivering oneself from the necessity of positive proof, but it is a very unscientific one. With respect to Rolph's assertion that pain can not be dispensed with, since it is everywhere the motive to action, it may be remarked that this statement seems to accord ill with Rolph's other theory that never the struggle for existence but always states of plenty and comfort are the conditions of growth, and the lengthy demonstration that periods of want must condition decline, retrogression, and finally the extinction of the species suffering the want. From the standpoint of Darwin, the struggle for existence is not inconsistent with the possession of plenty on the part of favored individuals and species, but Rolph expressly denies the compatibility of the two principles.

In his theory of want as the universal motive to action, Rolph cites suicide as an extreme case of this want. Our analysis has already taken into consideration some of the cases of mental struggle and postponement of the satisfaction of desire involving pain. But where one end greatly desired is unattainable, choice may yet be possible of another end affording partial satisfaction of the function corresponding to the desire, and, in cases where choice is necessary between two or more conflicting ends, the gratification of one may be attended with a sufficient degree of pleasure to cause partial forgetfulness of the disappointment in the necessary relinquishment of the other ends. Where, however, the function denied is one of the most fundamental of the organism, its denial may be combined with intensest pain and a gradual physical degeneration, or even a sudden collapse of the organism, ending in death; or it may induce an act that secures this end through the mediation of self-conscious will. What is true, in this case, of the denial of some one fundamental function, is true also of an accumulation of coincident denials of a number of lesser ones. Our desires are, indeed, in all cases, more or less complex, and involve the fulfilment of various functions; but we can easily imagine such an accumulation of small ills as to lead to desperation. Where no choice of action seems left us by which we may attain some one end deeply desired, or where a coincidence of obstacles makes it appear as if there were no choice of action towards any desirable ends, death may be chosen as a lesser evil than life, the equivalent of a lesser pain in the absence of feeling altogether. It may be noted, however, that where suicide is prevented in the first moment of desperation, the individual planning it may not only never again attempt it, but may afterwards even find much pleasure in life. As there is a high degree of pleasure connected with the performance of deeply rooted function or habit, so the performance of all function is attended with some modicum of pleasure, except in such isolated moments as render suicide possible. Every end desired is one of function, and all function furnishes ends to the will. The pessimist lays emphasis upon the fact of the speedy loss of pleasure in ends attained. But herein lies the higher pleasure of life, that it is not rest but progress. The pleasures we attain may be continually renewed if rightly sought, but they cannot be unintermittently sustained. We cannot rest at ends attained and find unlessened rapture in them. Rest is not an attribute of life; life is essentially motion, that phase of it which we term rest being mere change of function for a time. The intimate relation, between pleasure and an equilibrium of waste and repair renders it impossible to obtain pleasure except as occupation is varied in order to afford opportunity of recuperation to organs and cells before used. Proper variation, however, may enable us to return to old pleasures with ever renewed and even increased enjoyment. But it is conceivable that the pleasures of gratification and the pains of disappointment may be so nearly balanced as to make life possible and yet endow it, at least for a period, with but little joy. It is to be noticed, however, that intense pain cannot endure, unmodified, for any great length of time. As pleasure follows the line of customary action, so pain diminishes with long-continued lack in any direction, unless this direction be that of too fundamental function, in which case the organism succumbs entirely and perishes. Either we grow gradually used to our disappointment and forget it to a great degree in other gratification, or we die under it. Certainly there are losses the pain of which is never entirely forgotten, after which life is never quite the same again; but the first agony of such losses is materially modified with time; and many of the losses which have seemed worst to us at the time they occurred are later looked back upon without regret. We progress to another stage, and the ends we desire to gain are changed. The habitual misanthrope, indeed, generally derives a great deal of satisfaction from his own misery; and this leads us to the apparently anomalous remark that even pain as function may come to be combined with pleasure; we feel a satisfaction in our own capacity of emotion. The sensitivity of the poet to pain as well as his sensitivity to pleasure is a source of often very keen gratification and pride to him. Of the weak and aged who have no especial pleasure in life, it may be said that they have also, in general, no fierce pains, at least seldom such as bring desperation in youth. Having learned from experience, they are not subject to such exaggerated expectations, and hence disappointments, as accompany youth, vigor, and ignorance of the realities of life; and often they derive enjoyment from things which would have no attraction for the young.