Relatively little has previously been known about Paul Tillich’s teaching activities as Professor of Philosophy and Sociology at the University of Frankfurt (1929–1933). This volume of the new edition of Tillich’s Collected Works includes texts drawn from Tillich’s legacy, including the following lectures he gave between 1930 and the beginning of 1933: 1. Philosophy of religion; 2. The evolution of philosophy from late antiquity until the Renaissance; 3. Classical philosophy; 4. The history of philosophical ethics; and 5. Fundamental questions in systematic philosophy. In these lectures, Tillich inquires about life’s aporia, and reflects philosophically about their implications.