We know of three commentaries on Aristotle by Theodoricus de Magdeburg: The Quaestiones super De physica, the Quaestiones super De substantia orbis, and the Quaestiones super De anima. This paper presents an analysis of some of Thedoricus' s questions with regard to three main topics: Matter and Substance, God, and Man and Soul. The investigation of the first two works - and of the first two topics respectively - starts with an assessment of their contents. It turns out, however, that (...) Super De physica scarcely differs from super De substantia orbis and that the few differences are rather superficial. Theodoricus' s Super De anima mainly expounds the theory of the intellect. The analysis concentrates on his role in the debates with other Latin Averroists such as John of Jandun. It is evident that Theodoricus, even in his disagreement with other philosophers, essentially relies on Averroistic thought; but he also strikes out in new directions. These two characteristics of his philosophy - consistency and originality - mark him as an outstanding thinker in the tradition of Latin Averroism. (shrink)