Since the 12th century, questions about the celestial and sublunar world and the four elements were debated in university and scholastic settings on the basis of three works by Aristotle (384-322 BCE): De caelo, Meteorologica, and De generatione et corruptione. In his cosmological rubrics, Fra Mauro (active ca. 1430-ca. 1459/1464) cites the most prominent commentators on Aristotle: Islamic philosophers Avicenna (Ibn Sina, 980-1037) and Averroes (Ibn Rushd, 1126-1198) and Christian philosophers Albert the Great (ca. 1193-1280), Thomas Aquinas (ca. 1225-1274), and John of Holywood (ca. 1195-1256). Their commentaries covered a vast number of quaestiones in an effort to comprehend and bring up to date the three Aristotelian treatises on the physical world.
Fra Mauro explains the structure and functioning of the sublunar world by integrating the texts of these commentators with the Holy Scriptures and patristic theology, in particular the Genesis account of Creation and the related writings of Saint Augustine (354-430) and Thomas Aquinas. From St. Thomas’s Summa theologica, for example, Fra Mauro cites almost verbatim—but translated into Venetian vernacular—the entire passage on the number of heavens. Today this text by Fra Mauro stands as the only Venetian version of the Summa which has come down to us.