The Aristotelian commentaries by Petrus de Rivo, still unedited, represent a valuable instrument for our understanding of the major trends in the teaching of Aristotle at the fifteenth-century Faculty of Arts at Louvain. We published a preliminary survey of the manuscript material in last year’s issue of this journal, together with an account of the status quaestionis concerning Peter’s biography, works and the historical context of his thought. In the present article, we consider more closely a selection of his commentaries (...) on logic and natural philosophy. First, we offer an overview of Peter’s division of the sciences as expressed in his tractatus prohemiales, particularly those introducing his commentaries on Porphyry’s Isagoge and Aristotle’s Physics. Next, we considers Peter’s explanation of De interpretatione chapter 9, and his exposition of specific parts of Aristotle’s Physics and De anima. (shrink)