"I know that I am a thinking thing, and that I have an idea of God."

"I perceived it was possible to arrive at knowledge highly useful in life; and that, instead of the speculative philosophy usually taught in the Schools, we might find a practical, by means of which, k…"

"I think, therefore I am, is the first and most certain truth that occurs to anyone who philosophizes in an orderly way."

"It is not enough to apply our mind to things, but we must also apply it to ourselves."

"To be able to live without fear, without anxiety, without sadness, and without any other passion which could disturb the tranquillity of the soul."