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.

Only then, approaching my fortieth birthday, I made philosophy my life's work.

the essence of philosophy is not the possession of the truth but the search for truth. ... Philosophy means to be on the way. Its questions are more essential than its answers, and every answer becomes a new question.

Only a development of thought achieved through the self-education of the whole man can prevent any body of thought whatsoever from becoming a poison; can prevent enlightenment from becoming an agent of death.

A scientific approach means knowing what one knows and what one doesn't. Absolute or complete knowledge is unscientific.

The Greek word for philosopher (philosophos) connotes a distinction from sophos. It signifies the lover of wisdom (knowledge) as distinguished from him who considers himself wise in the possession of knowledge. This meaning of the word still endures: the essence of philosophy is not the possession of the truth but the search for truth. ... Philosophy means to be on the way. Its questions are more essential than its answers, and every answer becomes a new question.

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.