The egoistic-social impulses are always developed in children by their environment earlier than their erotic impulses can manifest themselves, except in a fragmentary and unsynthetized manner.

This is somewhat analogous to the situation of the plants that “time the explosions” of pollen maturity so as to secure cross-fertilization.

The child has no opportunity to synthetize his erotic impulses which become unified under the leadership of the reproductive organs at the time of puberty.

This separation of egoistic-social and erotic impulse development may have been Nature’s way of securing an excessive egoistic-social development, just as she secures maximum growth of the individual body about the time of puberty. It is obvious that where the struggle against the forces of nature is a keen one, as was the case ages ago before man had begun to coöperate and really to form the basis of social living, any development of the erotic impulse above the bare needs of propagation would have been impossible.

So it may be supposed that a high degree of development of the egoistic-social impulse was evolved out of the adverse conditions of the physical environment of the prehistoric man.

But today the intensity of this struggle against the forces of nature which developed the egoistic-social instinct is far less than ever before. And the fact that it is now comparatively so slight makes it evident that the original need for this excessive egoistic-social development has passed.

In this development the free expression of the erotic impulse was necessarily checked. One can see this process of inhibition of the erotic going on in present-day savage tribes who are still on the way from an uncivilized to a civilized condition. The sex activity of the individual is even in them restricted more or less to comply with the demands of the social unit.

It would seem that the expression of the erotic impulse would be freer and freer as we approached the ultimate goal of civilization. In uncivilized man, love in the sense used in this book has no existence, but sporadic instances of it appear among civilized peoples.

But the ascendancy gained, in early human life on the earth, over the erotic, by the egoistic-social instincts is now so great, on account of the comparative modernness of the higher type of erotic impulses, that even yet the latter are as young seedlings of some exotic plant in a forest of enormous trees.