Plato does not expressly insist that this tendency is of the nature of effort, though I think that is involved in his view. But Aristotle does. Following Plato in essentials, he makes bold to say outright that every natural thing in its own way longs for the divine and desires to share in the divine life, so far as it can.[11] Every such thing in this world of space and time has to cope with difficulties and is imperfect, but everything struggles towards the good. That good is in the life of God, a thinking life, an activity of thought, existing in some sense beyond this imperfect world; and this life is so supremely desirable that it makes everything else struggle to reach it. It moves the whole world, Aristotle says, in a famous passage, because it is loved. It is the world's desire.[12] Now this idea of effort--or of something analogous to effort--constituting the inner nature of every natural thing reappears, with pregnant consequences, in modern thought, though seldom with these vast theological consequences. The idea of an upward effort through nature lies at the base of our most hopeful theories of evolution, and forms the true support of our modern faith in progress. Broadly speaking, our evolutionists are now divided into two schools: the adherents of the one believe that variations are purely accidental, and may occur in any direction whatsoever, the useful ones being preserved only because they happen to be useful for the life of the species, while the adherents of the other--the school that I would call the school of hope--believe that accident, even with natural selection to aid it, is utterly inadequate to account for the ordered beauty and harmony that we do see in natural things. They admit, as Plato and Aristotle admit, imperfection and difficulty in the world, but they insist on a movement towards value: in short, they conceive an order emerging that is brought about, to quote a modern writer, both in nature and in society, by 'a principle of movement and progress conflicting with a principle of inertia.'[13] Aristotle, in words that are strikingly modern, raises the very question at issue here.[14] He asks whether we can suppose that nature does not aim at the good at all, but that variations arise by chance and are preserved just because they are useful, and he scouts the idea that chance could do more, as Zeller says, than 'bring about isolated and abnormal results'. He chooses instead the conception of purpose and effort, and this in spite of the difficulties in conceiving a purpose and an effort that are not definitely conscious. The sort of thing that is in Aristotle's mind when he speaks of nature aiming at the good, comes out in a passage by Edward Carpenter in his little book _The Art of Creation_. Carpenter plunges boldly and compares the principle that makes a tree grow and propagate its kind with the impulse that makes a man express himself. Man, he says,