In this text, I explore the contribution of the Dominican, Osmund Lewry, to medieval scholarship by focusing on his work on the medieval Dominican, Robert Kilwardby (1215-1279). I examine in some detail one area of Kilwardby's thought that was first noted by Lewry: the question of how the principles of scientific knowledge are acquired. In order to do so, I will briefly connect Kilwardby's answer to this question with those of his two more famous Dominican contemporaries, Albert the Great (ca. 1200-1280) and Thomas Aquinas (1224-1274). The aim of this paper is to give to provide a glimpse of the outstanding contribution of both Kilwardby and Lewry to the development of medieval philosophy and the scholarship on medieval philosophy.