The Euthydemus, though apt to be regarded by us only as an elaborate jest, has also a very serious purpose. It may fairly claim to be the oldest treatise on logic; for that science originates in the misunderstandings which necessarily accompany the first efforts of speculation. Several of the fallacies which are satirized in it reappear in the Sophistici Elenchi of Aristotle and are retained at the end of our manuals of logic.