prepossession is seen in the relation of parents, particularly of mothers, to children.  This begins, of course, among the lower animals.  The mammalian class, in particular, is distinguished by the strength and persistence of the devotion of parents to offspring.  The advantage secured by the form of reproduction characteristic of man and the other mammals is that a closer connection is secured between the child and the mother.  By the intra-uterine form of reproduction the association of mother and offspring is set up in an organic way before the birth of the latter, and is continued and put on a social basis during the period of lactation and the early helpless years of the child.  By continuing the helpless period of the young for a period of years, nature has made provision on the time side for a complex physical and mental type, impossible in types thrown at birth on their own resources.  Along with the structural modification of the female on account of the intra-uterine form of reproduction and the effort of nature to secure a more complex type and a better chance of survival, there is a corresponding development of the sentiments, and maternal feeling, in particular, is developed as the subjective condition necessary to carrying out the plan of giving the infant a prolonged period of helplessness and play through which its faculties are developed.[161] The scheme would not work if the mother were not more interested in the child than in anything else in the world.  In the course of development every variational tendency in mothers to dote on their children was rewarded by the survival of these children, and the consequent survival of the stock, owing to better nutrition, protection, and training.  Of course, this inherited interest in children is shared by the males of the group also, though not in the same degree, and there is reason to believe also that the interest of the male parent in children is acquired in a great degree indirectly and socially through his more potent desire to associate with the mother.

This interest and providence on the score of offspring has also a characteristic expression on the mental side.  All sense-perceptions are colored and all judgments biased where the child is in question, and affection for it extends to the particular marks which distinguish it.  Not only its physical features, but its dress and little shoes, its toys and everything it has touched take on a peculiar aspect.

On the organic side, therefore, there is developed a tendency, both in connection with reactions to stimulations in general and in connection with reproductive life in particular, to seize on particular aspects and to be obsessed by them to the exclusion or disparagement of other aspects.  The feelings of love and hate, and the broader feelings of race-prejudice and patriotism are consequently based first of all in the instincts.