until a comparative balance of fertility and mortality is reached as "human evolution approaches its limit of complete adaptation to the social state"; and sympathy will increase in proportion, no longer entailing on its possessor more of pain than of pleasure, but the contrary. "Sympathy is the root of every other kind of altruism than that which, from the beginning, originates the parental activities. It is the root of that higher altruism which, apart from the philoprogenitive instinct, produces desire for the happiness of others and reluctance to inflict pain upon them. These two traits are inevitably associated. The same mental faculty which reproduces in the individual consciousness the feelings that are being displayed by other beings, acts equally to reproduce those states when they are pleasurable or when they are painful." The general corollary from the above-described process of evolution is that, with the increase of sympathy there arises the double result, that by its increase it tends to decrease the causes of human misery, and in proportion as it does this, it becomes itself the cause of further reflected happiness received by each from others. "And the limit towards which this evolution approaches is one under which, as the amount of pain suffered by those around from individual imperfections and from imperfections of social arrangement and conduct, becomes relatively small, and simultaneously the growth of sympathy goes on with little check, the sympathy becomes at the same time almost exclusively a source of pleasure received from the happiness of others, and not of pains received from their pains. And as this condition is approached, the function of sympathy is not that of stimulating to self-sacrifice and of entailing upon its possessor positive or negative pain, but its function becomes that of making him a recipient of positive pleasure." Thus altruism will overgrow egoism, becoming itself a source of egoistic pleasure, and eventually, with the diminution of the pressure of population, there will come a state in which egoism and altruism are so conciliated that the one merges in the other. Among the social animals, with the ant and the bee, for instance, who cannot be supposed to possess a sense of duty, we see that this identification of egoism and altruism, as necessary to social life, has taken place to a considerable extent; and since pleasure of every kind is the concomitant of nervous structure, we can understand the pleasure in altruistic as well as in egoistic activities, as soon as there exists the nervous structure answering to these activities. As certainly as there yet exist in civilized men instincts of the chase inherited from savage ancestors, there are growing up and will continue to grow up in men, these other structures which will prompt to altruistic activities.