"Existentialism is a school of philosophic thought. The name is not like Platonism, Epicureanism, and Thomism. Existentialism is a nameless movement like pragmatism or positivism. This is deceptive. Existentialism owes its overriding significance to a single man: Heidegger. Heidegger alone brought about such a radical change in philosophic thought as is revolutionizing all thought in Germany, in continental Europe, and is beginning to affect even Anglo-Saxony. I am not surprised by this effect. I remember the impression he made on me when I heard him first as a young Ph.D. in 1922. Up to that time I had been particularly impressed, as many of my contemporaries in Germany were, by Max Weber, by Weber's intransigent devotion to intellectual honesty, by his passionate devotion to the idea of science, a devotion that was combined with a profound uneasiness regarding the meaning of science. On my way north from Freiburg where Heidegger then taught, I saw in Frankfurt am Main Franz Rosenzweig whose name will always be remembered when informed people speak about Existentialism, and I told him of Heidegger. I said to him: in comparison with Heidegger, Weber appeared to me as an orphan child in regard to precision, and probing, and competence. I had never seen before such seriousness, profundity, and concentration in the interpretation of philosophic texts."