§4. If, however, the individual is not likely to obtain a maximum of Pleasure by aiming merely at Preservation, it remains to consider whether ``quantity of life'' will serve any better. Now it is of course true that so far as nervous action is attended by consciousness pleasurable in quality, the more there is of it, the happier we shall be. But even if we assume that the more intense and full life is ``on the average'' the happier, it by no means follows that we shall gain maximum pleasure by aiming merely at intensity of consciousness: for we experience intense pains even more indubitably than intense pleasures, and in those ``full tides of soul'', in which we seem to be most alive, painful consciousness may be mixed in almost any proportion. And further we often experience excitement nearly or quite neutral in quality (i.e. not distinctly pleasurable or painful), which reaches a great pitch of intensity, as in the case of laborious struggles with difficulties, and perplexing conflicts of which the issue is doubtful.
It may, however, be replied that ``quantity of life'' must be taken to imply not merely intensity of consciousness, but multiplicity and variety---a harmonious and many-sided development of human nature. And experience certainly seems to support the view that men lose happiness by allowing some of their faculties or capacities to be withered and dwarfed for want of exercise, and thus not leaving themselves sufficient variety of feelings or activities: especially as regards the bodily organs, it will be agreed that the due exercise of most, if not all, is indispensable to the health of the organism; and further, that the health maintained by this balance of functions is a more important source of the individual's happiness than the unhealthy over-exercise of any one organ can be. Still, it would appear that the harmony of functions necessary to health is a very elastic one, and admits of a very wide margin of variation, as far as the organs under voluntary control are concerned. A man (e.g.) who exercises his brain alone will probably be ill in consequence: but he may exercise his brain much and his legs little, or vice versa, without any morbid results. And, in the same way, we cannot lay down the proposition, that a varied and many-sided life is the happiest, with as much precision as would be necessary if it were to be accepted as a basis for deductive Hedonism. For it seems to be also largely true, on the other side, that the more we come to exercise any faculty with sustained and prolonged concentration, the more pleasure we derive from such exercise, up to the point at which it becomes wearisome, or turns into a semi-mechanical routine which renders consciousness dull and languid. It is, no doubt, important for our happiness that we should keep within this limit: but we cannot fix it precisely in any particular case without special experience: especially as there seems always to be a certain amount of weariness and tedium which must be resisted and overcome, if we would bring our faculties into full play, and obtain the full enjoyment of our labour. And similarly in respect of passive emotional consciousness: if too much sameness of feeling results in languor, too much variety inevitably involves shallowness. The point where concentration ought to stop, and where dissipation begins, varies from man to man, and must, it would seem, be decided by the specific experience of individuals.
There is, however, another and simpler way in which the maxim of `giving free development to one's nature' may be understood: i.e. in the sense of yielding to spontaneous impulses, instead of endeavouring to govern these by elaborate forecasts of consequences: a scientific justification for this course being found in the theory that spontaneous or instinctive impulses really represent the effects of previous experiences of pleasure and pain on the organism in which they appear, or its ancestors. On this ground, it has been maintained that in complicated problems of conduct, experience will ``enable the constitution to estimate the respective amounts of pleasure and pain consequent upon each alternative'', where it is ``impossible for the intellect'' to do this: and ``will further cause the organism instinctively to shun that course which produces on the whole most suffering''. That there is an important element of truth in this contention I would not deny. But any broad conclusion that non-rational inclination is a better guide than reason to the individual's happiness would be quite unwarranted by anything that we know or can plausibly conjecture respecting biological evolution. For---overlooking the effect of natural selection to foster impulses tending to the preservation of the race rather than the pleasure of the individual, and granting that every sentient organism tends to adapt itself to its environment, in such a manner as to acquire instincts of some value in guiding it to pleasure and away from pain---it by no means follows that in the human organism one particular kind of adaptation, that which proceeds by unconscious modification of instinct, is to be preferred to that other kind of adaptation which is brought about by conscious comparison and inference. It rather seems clear, that this proposition can only be justified by a comparison of the consequences of yielding to instinctive impulses with the consequences of controlling them by calculations of resulting pleasure and pain. But it will hardly be maintained that in the majority of clear instances where non-rational impulse conflicts with rational forecast, a subsequent calculation of consequences appears to justify the former, the assertion would be in too flagrant conflict with the common sense and common experience of mankind. Hence, however true it may be that in certain cases instinct is on the whole a safer guide than prudential calculation, it would still seem that we can only ascertain these cases by careful reflection on experience: we cannot determine the limits to which prudential calculation may prudently be carried, except by this very calculation itself.
We seem, then, forced to conclude that there is no scientific short-cut to the ascertainment of the right means to the individual's happiness: every attempt to find a `high priori road' to this goal brings us back inevitably to the empirical method. For instead of a clear principle universally valid, we only get at best a vague and general rule, based on considerations which it is important not to overlook, but the relative value of which we can only estimate by careful observation and comparison of individual experience. Whatever uncertainty besets these processes must necessarily extend to all our reasonings about happiness. I have no wish to exaggerate these uncertainties, feeling that we must all continue to seek happiness for ourselves and for others, in whatever obscurity we may have to grope after it: but there is nothing gained by underrating them, and it is idle to argue. as if they did not exist.