"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 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."

“Humanam impotentiam in moderandis et coercendis affectibus servitutem voco; homo enim affectibus obnoxius sui juris non est sed fortunæ in cujus potestate ita est ut sæpe coactus sit quanquam meliora sibi videat, deteriora tamen sequi.”

“Meum institutum non est verborum significationem sed rerum naturam explicare”

“Hic conatus aliquid agendi et etiam omittendi ea sola de causa ut hominibus placeamus, vocatur ambitio præsertim quando adeo impense vulgo placere conamur ut cum nostro aut alterius damno quædam agamus vel omittamus; alias humanitas appellari solet.”

“veritas norma sui et falsi est”

“Ordo et connexio idearum idem est ac ordo et connexio rerum”

“[B]y Natura naturans we must understand what is in itself and is conceived through itself, or such attributes of substance as express an eternal and infinite essence, that is … God, insofar as he is considered as a free cause. But by Natura naturata I understand whatever follows from the necessity of God's nature, or from God's attributes, that is, all the modes of God's attributes insofar as they are considered as things which are in God, and can neither be nor be conceived without God.”