In keeping with the order found in traditional catalogues of Aristotle's works, Thomas Aquinas began his series of Aristotelian commentaries with a commentary on "On the Soul," which he followed with commentaries on "On Sense and What Is Sensed" and "On Memory and Recollection," written in 1268-70. Until now, these latter two commentaries have never been published in English translation. The translations presented in this volume are based on the critical Leonine edition of the commentaries and include English translations of the Aristotelian texts on which Aquinas commented. The translations of both commentaries are furnished with introductions and notes by the translators. Thomas's commentary on "On Sense and What Is Sensed" clarifies and develops Aristotle's discussion of sense-powers, his "application" of sensepowers to organs and objects, and his concluding questions concerning the object and medium of sensation, and the role of the "common sense." In "digressions" from his literal exposition, Aquinas presents discussions bearing on psychology, epistemology, natural philosophy, and metaphysics. The first three chapters of the commentary on "On Memory and Recollection" deal with memory and address three questions: "What is memory?" "To what part of the soul does memory belong?" and "What is the cause of remembering?" The last eight chapters, which deal with recollection, also address three questions: "What is recollection?" "How does recollecting take place?" and "What is the difference between memory and recollection?" In "digressions," Aquinas explores more fully the issues arising from the exposition of the text.