We may conclude our discussion of Nietzsche’s ontology of courage with the following quotation: “Have ye courage, O my brethren? . . . Not the courage before witnesses, but anchorite and eagle courage, which not even a God any longer beholdeth? . . . He hath heart who knoweth fear but vanquisheth it; who seeth the abyss, but with pride. He who seeth the abyss but with eagle’s eyes,—he who with eagle’s talons graspeth the abyss: he hath courage” (IV, 73, sec. 4). These words reveal the other side of Nietzsche, that in him which makes him an Existentialist, the courage to look into the abyss of nonbeing in the complete loneliness of him who accepts the message that “God is dead.” About this side we shall have more to say in the following chapters.

At this point we must close our historical survey, which was not meant to be a history of the idea of courage. It had a double purpose. It was supposed to show that in the history of Western thought from Plato’s Laches to Nietzsche’s Zarathustra the ontological problem of courage has attracted creative philosophy, partly because the moral character of courage remains incomprehensible without its ontological character, partly because the experience of courage proved to be an outstanding key for the ontological approach to reality. And further, the historical survey is meant to present conceptual material for the systematic treatment of the problem of courage, above all the concept of ontological self-affirmation in its basic character and its different interpretations.

[From Tillich’s Courage to Be]