"Except our own thoughts, there is nothing absolutely in our power."

"I have long ago observed that in order to study the truth, it is necessary once in the course of our life to demolish everything completely and start again from the foundations."

"The will, as far as it is considered formally in itself, is one of the chief perfections of man."

"I desire to live, and to continue the studies I have begun, but I have not found anyone who could tell me where to go."

"I am a thing that thinks, that doubts, that affirms, that denies, that wills, that refuses, that imagines also, and that perceives."