ABSTRACT
Roger Bacon read widely and his deep dependence on “Arabic” sources in Moralis philosophia, the last part of his Opus maius, is striking. He uses Abumasar, Algazel, al-Fārābī, Avicenna, Averroes, the Book of Causes, and even the Secretum secretorum, which he attributes to Aristotle. Surprisingly, Avicenna and, in particular, his Metaphysics 9.7 and 10.2–5, constitute by far Bacon’s main source, though he is fully aware that Avicenna wrote little on ethics. He uses Avicenna’s text as well as his other sources very openly but for his own purposes, and so twists and interprets them without paying attention to their original context—either because he did not know much about them or because he did not care.
