 Yet John clearly knew a great deal more about the doctrines of the classical Greek philosophers than this account might indicate. There were a number of Latin-language writers who transmitted to the Middle Ages accounts of Greek philosophical teachings, including Apuleius, Calcidius, Cicero, Seneca, Lactantius, and St. Augustine (O’Daly 2018). Thus, for example, John was aware of the existence of Plato’s Republic and some of its leading ideas, even though that text did not circulate in Europe until the fifteenth century (Dutton 1983; PC: 54, 137). He was also able to make considerable reference to Epicurus, albeit primarily filtered through the highly critical writings of Cicero and other Latin authors (Nederman and Bollermann 2011). And, the translated texts of ancient Greek thinkers sometimes contained passing references to other of their philosophical precepts, forming so-called “underground” sources (a term applied to John by Nederman and Brückmann 1983: 228–29). One instance of this is John’s use of key elements of Aristotelian ethical theory in his major writings, nearly one hundred years before the circulation of a Latin version of the Nicomachean Ethics, explicable by Aristotle’s occasional references to his moral principles in the Organon (Nederman 1997).