Virtually nothing is known about the life of Sextus Empiricus. He was a doctor and, as his name implies, a member of the Empiric school of medicine. He probably lived in the second century ce. His importance in the history of philosophy lies in the fact that he is the only ancient Greek sceptic whose complete works survive. Speci# cally, he belonged to the Pyrrhonist sceptical tradition, taking its inspiration from Pyrrho of Elis (c.360-c.270 bce), but organized as a systematic philosophical outlook in the early # rst century bce by Aenesidemus of Cnossos. Sextus’ surviving works are as follows: (i) Outlines of Pyrrhonism (herea" er PH, the initials of the title in Greek),1 which o% ers a general account of scepticism in the # rst book and, in the remaining two books, a critical assessment of non-sceptics’ views in logic, physics and ethics, the standard areas of philosophy in the Hellenistic period; (ii) a work in six books criticizing the pretensions to theoretical knowledge by experts in various specialized # elds such as rhetoric, mathematics and astrology, called Against the Professors (Adversus mathematicos in Latin, hence the standard abbreviation M); (iii) an incomplete work that originally covered the same ground as PH, but at much greater length; the surviving parts are Against the Logicians in two books, Against the Physicists in two books and Against the Ethicists in one book.2 Sextus’ own title for this work is Skeptika Hupomnēmata (Sceptical treatises). However, owing to a now unaccountable error in the manuscript tradition, these # ve surviving books were taken to be a continuation of the six-book work on specialized # elds; as a result, the logical books are known by the abbreviation M 7-8, the physical part by M 9-10 and the ethical part by M 11. For the subject of religion only PH and parts of the incomplete work are relevant.