"I concluded that I was a substance whose whole essence or nature consists only in thinking, and that, in order to exist, it needs no place and depends on no material thing."

"For the mind is not nourished by anything but truth."

"The nature of the mind is entirely distinct from that of the body."

"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 — this is the first and most certain conclusion that anyone who philosophizes in order should arrive at."