Until the launch of this series nearly twenty years ago, the 15,000 volumes of the ancient Greek commentators on Aristotle, written mainly between 200 and 600 AD, constituted the largest corpus of extant Greek philosophical writings not translated into English or other European languages. Over 40 volumes have now appeared in the series, which is planned in some 80 volumes altogether. Aspasius’ commentary on the Nicomachean Ethics , of which six books have come down to us, is the oldest surviving Greek commentary on any of Aristotle’s works, dating to the middle of the second century AD. It offers precious insight into the thinking and pedagogical methods of the Peripatetic school in the early Roman Empire, and provides illuminating discussions of numerous technical points in Aristotle’s treatise, along with valuable excursuses on such topics as the nature of the emotions. This is the first complete translation of Aspasius’ work in any modern language.