There flash back upon my memory all those dull, weary, sick human creatures, who have repeated to me that dull, weary, sick old formula, "You cannot change human nature." I do not think I am indulging either in religious superstition or in blind optimism, but am speaking precisely, in saying that whenever human beings get ready to apply experimental science to themselves, they can change human nature just as they now change plant nature. By putting human bodies together in love, we make new bodies of children more beautiful than any who have yet romped on the earth; and in the same way, by putting minds and souls together, we can make new kinds of minds and souls, different from those we have previously known, and greater than either the man-soul or the woman-soul alone. Also, by that magic which is the law of mind and soul life, each new creation can be multiplied to infinity, and shared by all other minds and souls that live in the present or may live in the future. We have shown elsewhere how genius multiplies to infinity the joy and power of life by means of the arts; and one of the greatest of the arts is the art of love. Consider the great lovers, the true lovers, of history--how they have enriched the lives of us all. It does not make any difference whether these men and women lived in the flesh, or in the brain of a poet--we learn alike from Dante and Beatrice, from Abelard and Heloise, from Robert and Elizabeth Browning, from Tristan and Isolde, from Romeo and Juliet, what is the depth and the splendor of this passion which lies hidden within us, and how it may enrich and vivify and glorify all life. PART FOUR THE BOOK OF SOCIETY CHAPTER XLVIII THE EGO AND THE WORLD (Discusses the beginning of consciousness, in the infant and in primitive man, and the problem of its adjustment to life.) We have now to consider the relationship of man to his fellows, with whom he lives in social groups. Upon this problem floods of light have been thrown by the new science of psycho-analysis. I will try to give, briefly and in simple language, an idea of these discoveries. One of the laws of biology is that every individual, in his development, reproduces the history of the race; so that impulses and mental states of a child reveal to us what our far-off ancestors loved and feared. The same thing is discovered to be true of neurotics, people who have failed in adjusting themselves to civilized life, and have gone back, in some or all of their mental traits, to infantile states. If we analyze the unconscious minds of "nervous patients," and compare them with what we find in the minds of infants, and in savages, we discover the same dreams, the same longings and the same fears.