Prodicus was born in Ceos, a little island belonging to the Athenian confederacy, and seems to have habitually resided at Athens. His health was delicate, and he wrapped up a good deal, as we learn from the ridicule of Plato, always pitiless to a valetudinarian.[F] Judging from two allusions in Aristophanes, he taught natural science in such a manner as to conciliate even that unsparing enemy of the new learning.[58] He also gave moral instruction grounded on the traditional ideas of his country, a pleasing specimen of which has been preserved. It is conveyed under the form of an apologue, entitled the Choice of Heraclês, and was taken down in its present form by Xenophon from the lips of Socrates, who quoted it, with full approval, for the benefit of his own disciples. Prodicus also lectured on the use of words, laying especial emphasis on the distinction of synonyms. We hear, not without sympathy, that he tried to check the indiscriminate employment of ‘awful’ (δεινός), which was even more rife at Athens than among ourselves.[G] Finally, we are told that, like many moderns, he considered the popular divinities to be personifications of natural phenomena. Hippias, who was a native of Elis, seems to have taught on very much the same system. It would appear that he lectured principally on astronomy and physics, but did not neglect language, and is said to have invented an art of memory. His restless inquisitiveness was also exercised on ancient history, and his erudition in that subject was taxed to the utmost during a visit to Sparta, where the unlettered people still delighted in old stories, which among the more enlightened Greeks had been superseded by topics of livelier and fresher interest. At Sparta, too, he recited, with great applause, an ethical discourse under the form of advice given by Nestor to Neoptolemus after the capture of Troy. We know, on good authority, that Hippias habitually distinguished between natural and customary law, the former being, according to him, everywhere the same, while the latter varied from state to state, and in the same state at different times. Natural law he held to be alone binding and alone salutary. On this subject the following expressions, evidently intended to be characteristic, are put into his mouth by Plato:—‘All of you who are here present I reckon to be kinsmen and friends and fellow-citizens, by nature and not by law; for by nature like is akin to like, whereas law is the tyrant of mankind, and often compels us to do many things which are against Nature.’[59] Here two distinct ideas are implied, the idea that Nature is a moral guide, and, further, the idea that she is opposed to convention. The habit of looking for examples and lessons to some simpler life than their own prevailed among the Greeks from a very early period, and is, indeed, very common in primitive societies. Homer’s similes are a case in point; while all that we are told about the innocence and felicity of the Aethiopians