In the family group, even as we observe it among many inferior vertebrates, we see that the parental sacrifice, now become so moderate in amount as to consist with long-continued parental life, is not accompanied by consciousness of sacrifice; but contrariwise, is made from a direct desire to make it: the altruistic labors on behalf of young are carried on in satisfaction of parental instincts. If we trace these relations up through the grades of mankind, and observe how largely love rather than obligation prompts the care of children, we see the conciliation of interests to be such that achievement of parental happiness coincides with securing the happiness of offspring: the wish for children among the childless, and the occasional adoption of children, showing how needful for attainment of certain egoistic satisfactions are these altruistic activities. And further evolution, causing along with higher nature diminished fertility, and therefore smaller burdens on parents, may be expected to bring a state in which, far more than now, the pleasures of adult life will consist in raising offspring to perfection while simultaneously furthering the immediate happiness of offspring. Now though altruism of a social kind, lacking certain elements of parental altruism, can never attain the same level, yet it may be expected to attain a level at which it will be like parental altruism in spontaneity--a level such that ministration to others' happiness will become a daily need--a level such that the lower egoistic satisfactions will be continually subordinated to this higher egoistic satisfaction, not by any effort to subordinate them, but by the preference for this higher egoistic satisfaction whenever it can be obtained. Let us consider how the development of sympathy, which must advance as fast as conditions permit, will bring about this state. § 93. We have seen that during the evolution of life, pleasures and pains have necessarily been the incentives to, and deterrents from, actions which the conditions of existence demanded and negatived. An implied truth to be here noted is, that faculties which, under given conditions, yield partly pain and partly pleasure, cannot develop beyond the limit at which they yield a surplus of pleasure: if beyond that limit more pain than pleasure results from exercise of them, their growth must be arrested.