"I am certain that I am a thinking thing, and that I have a body, and that I am distinct from my body."

"The mind is more easily known than the body."

"I am accustomed to take my sleep for granted, and I often imagine that I dream of the most important things, when after all I am only dreaming."

"To be possessed of a vigorous mind is not enough; the prime requisite is rightly to apply it."

"The preservation of health has always been the principal end of my studies."