A few words may be added regarding another aspect of Athenian greatness during the period of the democracy, which has already been incidentally mentioned. The latter half of the fifth century B.C., which was the golden age of the sophists, also saw the rise of a new intellectual movement, which was destined to secure for Athens a position of supremacy in the department [Illustration: THE ACROPOLIS, WITH KALLIRRHOÈ IN THE FOREGROUND The worn and polished bed of the Ilissus, down which trickles the water of the fountain of Kallirrhoè, is richly coloured with blue and purple, owing to reflected light from the blue sky of a brilliant early morning in summer. The Acropolis, with the Parthenon (divided into two masses from this point of view), is relieved against the sky. To the right are some of the lofty columns of the Temple of Olympian Zeus, the little café or refreshment house giving scale to them.] of philosophy for hundreds of years after it had sunk into political insignificance, and even after the sceptre in the realm of literature had passed to Alexandria. The man to whom this new departure was chiefly due was Socrates, a brave soldier, a genial friend, and an incorruptible citizen, as well as an original thinker. Greatly to his own astonishment, he was declared by the Delphian oracle to be the wisest of men--a statement which he could only credit in the sense that he was wiser than others inasmuch as he was aware of his own ignorance. He not only imparted a higher moral tone to the teaching of Greek philosophy than it ever had before, but also laid the foundation of the Logic of Definition, and anticipated in the sphere of ethics the principle of Induction on which Aristotle acted in the next century in various departments of his encyclopædic studies, and which was to be fully applied by Lord Bacon in the natural world nearly 2000 years afterwards. Before the days of Socrates the greatest, or at least the most ambitious, thinkers had made vain attempts to unveil the secrets of the physical universe, and in doing so had either ignored the traditional theology, or else explained it away, like Xenophanes, who held that the gods were the creation of human imagination, and that if oxen or lions were to become religious they would likewise make for themselves gods in their own image. With such impiety Socrates could have no sympathy, as we may judge from the fact that he even condemned the presumption of Anaxagoras in treating _Helios_ and _Selené_ (sun and moon) as if they were material bodies, whose motions and magnitudes could be ascertained by the intellect of man.