 The major source for Epicurean doctrine is Diogenes Laertius’ third-century C.E. Lives of Eminent Philosophers, a compilation of information on the lives and doctrines of the philosophers of classical Greece (see “Doxography of Ancient Philosophy”). In the tenth and final book, devoted to Epicureanism, Diogenes preserves three of Epicurus’ letters to his disciples, in which he presents his basic views in a concise and handy form. The Letter to Herodotus summarizes Epicurus’ physical theory, the Letter to Menoeceus offers a précis of Epicurean ethics, and the Letter to Pythocles treats astronomical and meteorological matters. (There is some doubt about whether the last is by Epicurus himself or a follower, but there seems to be sufficient reason to attribute it to the founder himself.) Diogenes also quotes a collection of brief sayings, called the “Principal Beliefs” or “Principal Doctrines” (Kuriai Doxai), excerpted from the writings of Epicurus or, in some cases, of his close associates; another such collection, partially overlapping with the first, survives in an independent manuscript and is conventionally called the Vatican Sayings. The purpose of both sets, like that of the Letters, was to make the core doctrines easy to remember. Diogenes also fills in topics not covered in the Letters, and provides a list of Epicurus’ writings and other biographical information (for the text, see Dorandi 2013; for an English translation, Mensch 2018). 