Aryeh Motzkin was an extraordinary thinker and writer. Much of his work appeared in small academic journals despite the fact that it is often quite accessible, even to non-experts. This volume assembles his most important published papers along with several unpublished papers. They all have a single theme: the encounter between the Jewish tradition and philosophy as discovered by Plato and Aristotle. The book’s first group of essays deal with the way medieval Jewish thinkers understood the philosophies of Plato and Aristotle. The second group deals with how these same medieval thinkers were themselves interpreted by modern thinkers, beginning with Spinoza. A recurring issue in all the essays is the difficulty inherent in any encounter between philosophia perennis and the changing history of Judaism.