But it is when we come to the highest level that we find even more subtle ways planned to accomplish the desired end.  Here we enter the realm of individual initiative, for it is not now enough to leave to external forces the joining of the two life-elements.  In order to make a new individual, father and mother must be drawn together, and so there enters into the situation a personal relationship with all that that implies.  Because Nature has had to provide ways of drawing individuals to one another, she has put into the higher types of life the power of mutual attraction,—­a power which in man, the highest of all types, is responsible for many outgrowths that seem far removed from the original purpose.

=The Love-Motif.= On the one hand, there is the persistent desire to be attractive, which manifests itself in the subtlest ways.  How many of the yearnings and activities of human life have their roots in this ancient and honorable desire!  The love of pretty clothes,—­however it may seem to be motivated and however it may be complicated by other motives,-draws its energy, fundamentally, from the same need that provides the gay plumage and limpid song of the bird or the painted wings of the butterfly.

On the other hand, there is the capability of being attracted, with all the personal relationships which spring from the power of admiring and loving another person.  The interest in others does not expend its whole force on its primary objects,—­mate and children.  It flows out into all human relationships, developing all the possibilities of loving which mean so much in human life; the love of man for man and woman for woman, as well as mutual love of man and woman.  A force like this, once planted, especially in the higher types of life, does not spend all its energies in its main trunk.  It sends out branches in many directions, bearing by-products which are rich in value for all of life.

Many of our richest relationships, our best impulses, and our most firmly fixed social habits spring from the family instincts of reproduction and parental care.  The social life of our young people, so well calculated to bring young men and women together; all the beauty of family life and, as we shall later see, all the broader benevolent activities for society in general, are energized by the same love-instincts which form so large a part of human nature.

LEARNING TO LOVE

=A Four-Grade School.= It is impossible to watch the growth of the love-life of a human being, to trace its development from babyhood up to its culmination in mating and parenthood, without a sense of wonder at the steady purpose behind it all.  We used to believe that the love for the young girl that suddenly blooms forth in the callow youth was an entirely new affair, something suddenly planted in him as he developed into manhood; but now we know, thanks to the uncovering of human nature by the painstaking investigations