This nature that we return to, haunts our thoughts as a fixed state in which the wise soul can find enduring refuge. Just how we get the idea that nature is stable, is not easy to see; the notion often exists in our minds side by side with a deep conviction that life is a flux, and that time and space are but relative terms in the universal stream. But perhaps it is the outer appearance of the world, nature as landscape, that first suggests a refuge even against time, mountains are so immovable in their mysterious silence for us as for Wordsworth, the ocean is so untamable for us, as it was for Byron. Perhaps also the contemplation of the changing universe during the past century of daring and imaginative science has endowed nature with a romantic career of its own, such as the old humanists ascribed only to men; perhaps the progress of stars, planets and solar systems, observed or guessed at, suggests in spite of the evolution it illustrates a deeper kind of rest in the laws by which that evolution conducts itself; so that the last result of turning from human art to watch the behavior of inanimate things is the conviction that nothing is really inanimate, but that all move in the wisdom of an art superhuman, in an order peaceful and eternal as only a divine vitality could conceive. When we think of nature in this sense of the word, leaving man out of the picture, ourselves too as far as possible who do the thinking, we are ready to say with Emerson that art is an impertinent intrusion, nature is all. “Nature in the common sense refers to essences unchanged by man; space, the air, the river, the leaf; art is applied to the mixture of his will with the same things, as in a house, a canal, a statue, a picture; but his operations taken together are so insignificant,—a little shaping, baking, patching and washing,—that in an impression so grand as that of the world on the human mind they do not vary the result.” We can speak of nature in this all-embracing way so long as, like Emerson for the moment, we lay aside every thought of man and of the moral world which he creates or brings under his control, and in which his responsibility is fixed. But once we resume that human outlook, we begin to use the word natural in at least two other senses. In the first place we use it to describe the process of life, that constant birth or becoming which seems to have been present to the mind of the Greek also when he used his word for nature—as when Aristotle says, in a famous phrase, that art is an imitation of nature, meaning that the process of art is a copy of the processes of birth and becoming, and creates by the same methods that life does. In this sense of the word nature is like art, not opposed to it, and with this interpretation Polixenes tried to rebuke the cult of the natural in Perdita, who would not have in her garden a flower artificially bred: