The Greeks in their sanity discovered not only the natural world but the art of living well in it. Besides physics they founded ethics and politics. But here again progress was prevented by the rejection or perversion of the greater thing in the interests of the lesser. Speculatively at least some just conception of the world we live in, and of our place and destiny there, is more important than the choice of a definite way of life; for animals and man have, quite legitimately, each his own habits and pleasures, but they all crawl under the same heaven, and if they think of it at all, they should not blaspheme against it. The Greek naturalists had conceived nature rightly; and their sentiments and maxims, whilst very properly diverse, had all of them a certain noble frankness in the presence of the infinite world, of which they begged no favours. It was precisely these personal sentiments and maxims, and policy in the government of cities, that interested the Greeks most; and the Sophists and Socrates affected to care nothing about natural science, unless it could make their pot boil. This utilitarianism was humorous in Socrates, and in some of the Sophists unprincipled; but the habit of treating opinions about nature as rhetorical themes, or as more or less edifying myths, had disastrous consequences for philosophy. It created metaphysics. Metaphysics is not merely speculative physics, in which natural science is extended imaginatively in congruous ways, anticipating what might some day be discovered. This is what the naturalists had done, and their theories were simply physical or cosmological. But after Socrates a theory constructed by reasoning, in terms of logic, ethics, and a sort of poetic propriety was put in the place of physics; the economy of the human mind was projected into the universe; and nature, in the works of the metaphysicians, held the mirror up to man. Human nature and the human mind, which were thus made to rule the world, are in reality a very small incident in it; they are proper to one animal; they are things of yesterday and perhaps not of to-morrow. This is nothing against them in their place, as it is nothing against the daisy that it is humble, nor against the spray of the sea that its flight is violent and brief. The Platonic, British, and German schools of philosophy advance our knowledge of ourselves; what a pity that they were not content to cultivate their own gardens, where so many moral fruits and psychological flowers might be made to grow, but have insisted that their domestic vegetables are the signs of the zodiac, and that the universe was made to illustrate their horticulture!