Walter Kaufmann spent 33 years (1947-1980) teaching philosophy at Princeton. And more than anyone else, Kaufmann introduced Nietzsche's philosophy to the English-speaking world and made it possible to take Nietzsche seriously as a thinker – something there wasn't always room to do in American intellectual circles.
Without simplifying things too much, Kaufmann saw Nietzsche as something of an early existentialist, which brings us to these vintage lectures recorded in 1960 (right around the time that Kaufmann, a German-born convert to Judaism, also became a naturalized American citizen). The three lectures offer a short primer on existentialism and the modern crises philosophers grappled with. Kierkegaard and the Crisis in Religion begins the series, followed by Nietzsche and the Crisis in Philosophy and Sartre and the Crisis in Morality.
Kaufmann's talks are now listed in the Philosophy section of our collection of Free Online Courses. There you will also find courses presented by more contemporary philosophers, including John Searle, Hubert Dreyfus, and Michael Sandel.