Aristotle's "Meterology Book 4" provides an account of the formation of minerals, metals and other homogeneous stuffs. In doing so, this text argues, it offers us fresh and important insights into Aristotle's conception of matter. The 15,000 pages of the ancient Greek commentators on Aristotle, written mainly between 200 and 600 AD, constitute the largest corpus of extant Greek philosophical writing not translated into English or other European languages. This is a new series of translations, planned in 60 volumes which fills an important gap in the history of European thought.