 Thus, what prima facie seems to be a major difference between Galen and Sanches regarding the truths mathematics may not be so great after all. Doubtlessly, Galen was an Aristotelian philosopher and physician, who subscribed to Aristotelian logic and definitions, whereas Sanches was not and did not; and yet much like Sanches he doubted that any knowledge of the noumenal world (e.g., God, the substance and immortality of the soul, etc.) was possible. Interestingly, Galen’s “An Outline of Empiricism” begins with the following sentence: 