"His correspondence is the most interesting book one can read in the world of uprightness and of humanity."

“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.”