"Spinoza was the man I believed in always, as the alternative to Catholicism. And it is only in Spinoza's manner that I am a positivist at all. I believe in the real world, in the world of thought and extension, of psychology and physics. God or substance with Spinoza equals reality; and this reality, which may have countless forms, we find only in space and in (other men's) consciousness. I say in other men's, because Spinoza was too sane to care to discuss anything from the point of view of subjective idealism. When one prints a book to convince other people, one oughtn't to discuss in it whether they exist. But this is all by the way, although some other day I will discuss with you the question of Spinoza's hedonism."