celebrated author of the Pyrrhonian Hypotheses, was a physician who attached himself to the school of the Empirici, and hence the name by which he is usually known. He was a pupil of Herodotus of Tarsus (Diog. Laërt. ix. Timan), who was himself a physician, and most probably a contemporary of Galen. This serves to settle, with some degree of accuracy, the era of Sextus, who must have flourished about the first half of the third century after Christ. Nothing whatever is known of his life. He has given full proof to all succeeding thinkers in the two books which he has left behind him, of the precise complexion of his creed, and the amount of ingenuity with which he was capable of defending it. The first work, Ἐπιστολαὶ Πυρρωτεύουσας ἐν ὑποκρίσει, contains a complete repository of the doctrines of the sceptics. His second work, Ἐπιστολαὶ μαθηματικῶν διαφοροῦσας, in eleven books, is against the mathematicians, or dogmatists, and attempts to refute every vestige of positive knowledge which man has ever elaborated. The works combined form the most correct account extant of the ancient sceptical thinkers, and their mode of assailing all manner of dogmatism. It is a perfect store-house of doubts regarding every imaginable phase of human knowledge. It is set forth with eminent clearness, and contains an exposition of the doctrines maintained by the sceptical school. Sextus now and then degenerates into pure logomachy, a thing to be expected, but with this exception, it is really wonderful the amount of acute pertinacious pursuit with which every idea, real or supposed, is hunted down and strained into the sceptical alembic. He enunciates at the outset what he understands by scepticism. It is, he says, a disposition to doubt of everything beyond mere phenomena. Sextus carries out this definition with the most rigid exactness. It is, without doubt, one of the most refreshing books that a man of reflection can meet with, and it is really surprising to find that the same everlasting problems, which, sixteen centuries ago, were perplexing the minds of thinking men, are still occupying the attention and exciting the passions of philosophers, and apparently will do so to the very end. For an account of the tenets of this author see Scepticism. The Editio Princeps of the Greek text of Sextus was that of Paris and Geneva, 1621. The second impression of the works of Sextus Empiricus was by J. A. Fabricius, Leipzig, 1718. A good edition of the Greek text is that of Bekker, Berlin, 1842. The first Latin translation of the Hypo- Seychelles *typoses* was published by H. Stephens, in 1562. The first Latin version of the work against the Dogmatists is by G. Hervet, Antwerp and Paris, 1569. Bubbe translated the *Hypotyposes*, or outlines, in 1801; and there is an anonymous French version, or rather paraphrase, of them, supposed to be by one Huart, a teacher of mathematics, published in 1725. An English version of the works of Sextus is still a desideratum; but the text would require considerable purification before a respectable translation could be executed. None of the medical works of Sextus remain.