There can be no doubt as to Aristotle's marvellous power of systematizing. Collecting together all the results of ancient speculation, he so combined them into a co-ordinate system that for a thousand years he reigned supreme in the schools. From a literary point of view, Plato was doubtless his superior; but Plato was a poet, making philosophy divine and musical, while Aristotle's investigations spread over a far wider range. He differed from Plato chiefly in relation to the doctrine of ideas, without however resolving the difficulty which divided them. As he made matter to be the eternal ground of phenomena, he reduced the notion of it to a precision it never before enjoyed, and established thereby a necessary element in human science. But being bound to matter, he did not soar, as Plato did, into the higher regions of speculation; nor did he entertain as lofty views of God or of immortality. Neither did he have as high an ideal of human life; his definition of the highest good was a perfect practical activity in a perfect life. With Aristotle closed the great Socratic movement in the history of speculation. When Socrates appeared there was a general prevalence of scepticism, arising from the unsatisfactory speculations respecting Nature. He removed this scepticism by inventing a new method of investigation, and by withdrawing the mind from the contemplation of Nature to the study of man himself. He bade men to look inward. Plato accepted his method, but applied it more universally. Like Socrates, however, ethics were the great subject of his inquiries, to which physics were only subordinate. The problem he sought to solve was the way to live like the Deity; he would contemplate truth as the great aim of life. With Aristotle, ethics formed only one branch of attention; his main inquiries were in reference to physics and metaphysics. He thus, by bringing these into the region of inquiry, paved the way for a new epoch of scepticism.