It is just possible that an incorrect analysis of instincts led him to stress this point. Taking a suggestion of Epicurus that fear is the cause of abnormal behavior, he drove it hard. He seems not to have surmised that fear of death was readily to be explained as an inheritance from those who had most successfully shunned death; instead he sought to explain the instinct for self-preservation by superstition and to blame that superstition for the acts that are in fact induced by a powerful instinct. How he asks, could a man let greed so dominate him that he would steal, deceive, and even murder, unless he were driven by an inordinate desire to escape the want which might bring death and suffering after death? Such is the argument which seems to be largely his own. In his purpose then, he is wholly sincere, whatever we may think of the logic of his argument. However, he betrays in his enthusiasms the fact that what inspires him is not a negative missionary spirit, but the desire to let every man know the beauty of science. Plato spoke of the hypnotic vision of “ideas”—the ecstatic thrill that came to the philosopher who penetrated into divine knowledge. We know with what enthusiasm Sir Isaac Newton’s announcement of the laws of gravitation was greeted, with what joy scientists in our own day heard of the breaking-up of the atom and of the cosmic rays that penetrate our atmosphere. Similar must have been the exaltation of this Roman when he felt that he could lay aside childish superstitions, suddenly pierce the confines of the universe and behold the nebulae shaping into planets, when he realized, as he thought, that energy lived forever, that matter was eternal, that the universe was infinite, that in the survival of the fit there were promises of eternal progress, that law and order ruled the universe. His ibi me rebus quaedam divina voluptas percipit atque horror. It amazed him to find himself so carried away that he could not sleep, that he must sit the whole night through satisfying his soul with the vision he had caught. Materialism has been called an unpoetic theme. To us it may be, but to a Roman brought up in the dull mazes of polytheism and the ludicrous nursery-tales that masqueraded as cosmology, it was a sudden liberation. He had found a theme of the highest poetic worth, the epic story of the origins of life; and Vergil who half rejected his arguments still was poet enough to see that Lucretius had discovered the sublimest of all poetic themes—_Felix qui potuit_.