I began the study of medicine, impelled by a desire for knowledge of facts and of man. The resolution to do disciplined work tied me to both laboratory and clinic for a long time to come.

Even scientific knowledge, if there is anything to it, is not a random observation of random objects; for the critical objectivity of significant knowledge is attained as a practice only philosophically in inner action.

The history of philosophy is not, like the history of the sciences, to be studied with the intellect alone. That which is receptive in us and that which impinges upon us from history is the reality of man's being, unfolding itself in thought.

What makes us afraid is our great freedom in the face of the emptiness that has still to be filled.

Philosophic meditation is an accomplishment by which I attain Being and my own self, not impartial thinking which studies a subject with indifference.

The more determinedly I exist, as myself, within the conditions of the time, the more clearly I shall hear the language of the past, the nearer I shall feel the glow of its life.

To decide to become a philosopher seemed as foolish to me as to decide to become a poet.