AS soon as we begin to think about the world around us in what we vainly call a disinterested way—for disinterest is, as Leibnitz said, a chimera, and there remains a superior interest—we become youths and lovers and artists, and there is at the same time a significant strain of sexual imagery in our thought.[44] Among ourselves this is not always clear; we have been dulled by the routine of civilisation and the artificial formalities of what is called education. It is clear in the mythopœic creation of comparative primitive thought, but in civilisation it is in the work of men of genius—poets, philosophers, painters, and, as we have to recognise, men of science—that this trait is most conspicuously manifested. To realise this it is sufficient to contemplate the personality and activity of one of the earliest great modern men of science, of Leonardo da Vinci. Until recent times it would have seemed rather strange so to describe Leonardo da Vinci. He still seemed, as he was in his own time, primarily a painter, an artist in the conventionally narrow sense, and as such one of the greatest, fit to paint, as Browning put it, one of the four walls of the New Jerusalem. Yet even his contemporaries who so acclaimed him were a little worried about Leonardo in this capacity. He accomplished so little, he worked so slowly, he left so much unfinished, he seemed to them so volatile and unstable. He was an enigma to which they never secured the key. They failed to see, though it is clearly to be read even in his face, that no man ever possessed a more piercing concentration of vision, a more fixed power of attention, a more unshakable force of will. All that Leonardo achieved in painting and in sculpture and in architecture, however novel or grandiose, was, as Solmi, the highly competent Vincian scholar has remarked, merely a concession to his age, in reality a violence done to his own nature, and from youth to old age he had directed his whole strength to one end: the knowledge and the mastery of Nature. In our own time, a sensitive, alert, widely informed critic of art, Bernhard Berenson, setting out with the conventional veneration for Leonardo as a painter, slowly, as the years went by and his judgment grew more mature, adopted a more critical attitude, bringing down his achievements in art to moderate dimensions, yet without taking any interest in Leonardo as a stupendous artist in science. We may well understand that vein of contempt for the crowd, even as it almost seems the hatred for human society, the spirit of Timon, which runs across Leonardo’s writings, blended, no doubt inevitably blended, with his vein of human sweetness. This stern devotee of knowledge declared, like the author of “The Imitation of Christ,” that “Love conquers all things.” There is here no discrepancy. The man who poured a contemptuous flood of irony and denunciation over the most sacred social institutions and their most