Though races of men are contrasted with one another so much less than genera and orders of animals are, yet, as we saw in the last chapter, along with visible differences there go invisible differences, with accompanying likings for different modes of life. Among some, as the Mantras, the love of unrestrained action and the disregard of companionship, are such that they separate if they quarrel, and hence live scattered; while among others, as the Damaras, there is little tendency to resist, but instead, an admiration for any one who assumes power over them. Already when exemplifying the indefiniteness of happiness as an end of action, I have referred to the unlike ideals of life pursued by the nomadic and the settled, the warlike and the peaceful--unlike ideals which imply unlikenesses of nervous structures caused by the inherited effects of unlike habits accumulating through generations. These contrasts, various in their kinds and degrees among the various types of mankind, every one can supplement by analogous contrasts observable among those around. The occupations some delight in are to those otherwise constituted intolerable; and men's hobbies, severally appearing to themselves quite natural, often appear to their friends ludicrous and almost insane: facts which alone might make us see that the pleasurableness of actions of this or that kind, is due not to anything in the natures of the actions but to the existence of faculties which find exercise in them. It must be added that each pleasurable emotion, like each pleasurable sensation, is relative not only to a certain structure but also to the state of that structure. The parts called into action must have had proper rest--must be in a condition fit for action; not in the condition which prolonged action produces. Be the order of emotion what it may, an unbroken continuity in the receipt of it eventually brings satiety. The pleasurable consciousness becomes less and less vivid, and there arises the need for a temporary cessation during which the parts that have been active may recover their fitness for activity, and during which also the activities of other parts and receipt of the accompanying emotions may find due place.