Besides these excellent contributions to the subject, Prince Kropotkin gives us other new and striking thoughts, bearing upon the parental source of the social feelings indicated by Darwin. But first let us go back to Darwin. In Chapter Four of _The De-scent of Man_ Darwin says: The feeling of pleasure from society is probably an extension of the parental or filial affections, since the social instinct seems to be developed by the young remaining for a long time with their parents, and this extension may be attributed in part to habit, but chiefly to natural selection. With those animals which were benefited by living in close association, the individuals which took the greatest pleasure in society would best escape various dangers, whilst those that cared least for their comrades, and lived solitary, would perish in greater numbers. Dr. Saleeby, in the _Academy_ in the spring of 1905, had some interesting remarks upon the origin of altruism. He "finds in the breast of the mammalian mother the fount whence love has flowed," and points out that the higher we go in the mammalian scale the more dependent are the young upon their mothers. After describing the helplessness of the human baby, he continues thus: Yet, this is the creature which has spread over the earth so that he numbers some fifteen hundred millions to-day. He is the "lord of creation," master of creatures bigger, stronger, fleeter, longer-lived than himself. The earth is his and the fulness thereof. Yet without love not one single specimen of him has a chance of reaching maturity, or even surviving for a week. Verily love is the greatest thing in the world. Well, upon this subject of the parental origin of altruism, Prince Kropotkin throws another light. First, alluding to Darwin's cautious handling of the subject of the maternal origin of social feelings, Prince Kropotkin, quotes Darwin's own remarkable comment, thus: This caution was fully justified, because in other places he pointed out that the social instinct must be a _separate instinct in itself_, different from the others--an instinct which has been developed by natural selection _for its own sake_, as it was useful for the well-being and preservation of the species. It is so fundamental, that when it runs against another instinct, even one so strong as the attachment of the parents to their offspring, it often takes the upper hand. Birds, when the time has come for their autumn migration, will leave behind their tender young, not yet old enough for a prolonged flight, and follow their comrades. He then offers the following suggestion: