Book excerpt: “Scrupulously prepared and eminently readable,” this volume presents Heidegger’s most important lectures on religion from 1920–21 (Choice). In the early 1920s, Martin Heidegger delivered his famous lecture course, Introduction to the Phenomenology of Religion, at the University of Freiburg. He also prepared notes for a course on The Philosophical Foundations of Medieval Mysticism that was never delivered. Though he never prepared this material for publication, it represents a significant evolution in his philosophical perspective. Heidegger’s engagements with Aristotle, Neoplatonism, St. Paul, Augustine, and Martin Luther give readers a sense of what phenomenology would come to mean in the mature expression of his thought. Heidegger reveals an impressive display of theological knowledge, protecting Christian life experience from Greek philosophy and defending Paul against Nietzsche.