Rationalism

It was by no means idiosyncratic for Kant to take Plato and Aristotle as prefiguring the opposition between rationalism and empiricism; this opposition is, for example, the organizing principle of Raphael's Vatican fresco The School of Athens. Plato points up, to the realm of Forms, the unchanging objects of the pure intellect; Aristotle points to the earth, thereby indicating the experiential origin of knowledge. Plato's commitment to the existence of unchanging truths, sharply contrasted with the variable images of the senses, marks him as the grandfather of early modern rationalism.

Approximately five hundred years later, Saint Augustine synthesized Plato's philosophy with the Christian religion in order to provide the latter a philosophical underpinning. Augustine found in Plato a remedy for the vagaries of sense experience that threatened the truth of Christianity; his work remained seminal for the early modern rationalists: Descartes, Leibniz, and Malebranche, believers all, explicitly hearkened back to Augustine. Aristotle's work, however, held its importance for medieval philosophers. He became known as "the Philosopher," and his thought, especially as interpreted by Aquinas, became the official philosophy of Christianity.