If we further reflect that, as many investigators believe, not only the physical structure of life but also its spiritual structure--our social feelings, our morality, our religion, our poetry and art--are, in some degree at least, also built up on the impulse of sex, and would have been, if not non-existent, certainly altogether different had other than sexual methods of propagation prevailed in the world, we may easily realize that we can only fall into confusion by dismissing love as a delusion. The whole edifice of life topples down, for as the idealist Schiller long since said, it is entirely built up on hunger and on love. To look upon love as in any special sense a delusion is merely to fall into the trap of a shallow cynicism. Love is only a delusion in so far as the whole of life is a delusion, and if we accept the fact of life it is unphilosophical to refuse to accept the fact of love. It is unnecessary here to magnify the functions of love in the world; it is sufficient to investigate its workings in its own proper sphere. It may, however, be worth while to quote a few expressions of thinkers, belonging to various schools, who have pointed out what seemed to them the far-ranging significance of the sexual emotions for the moral life. "The passions are the heavenly fire which gives life to the moral world," wrote Helvétius long since in _De l'Esprit_. "The activity of the mind depends on the activity of the passions, and it is at the period of the passions, from the age of twenty-five to thirty-five or forty that men are capable of the greatest efforts of virtue or of genius." "What touches sex," wrote Zola, "touches the centre of social life." Even our regard for the praise and blame of others has a sexual origin, Professor Thomas argues (_Psychological Review_, Jan., 1904, pp. 61-67), and it is love which is the source of susceptibility generally and of the altruistic side of life. "The appearance of sex," Professor Woods Hutchinson attempts to show ("Love as a Factor in Evolution," _Monist_, 1898), "the development of maleness and femaleness, was not only the birthplace of affection, the well-spring of all morality, but an enormous economic advantage to the race and an absolute necessity of progress. In it first we find any conscious longing for or active impulse toward a fellow creature." "Were man robbed of the instinct of procreation, and of all that spiritually springs therefrom," exclaimed Maudsley in his _Physiology of Mind_, "that moment would all poetry, and perhaps also his whole moral sense, be obliterated from his life." "One seems to oneself transfigured, stronger, richer, more complete; one _is_ more complete," says Nietzsche (_Der Wille zur Macht_, p. 389), "we find here art as an organic function: we find it inlaid in the most angelic instinct of 'love:' we find it as the