Rene Descartes — "He who has a firm and stable mind will find that in all conditions of life he ca…"

"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…"

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

"The light of natural reason is sufficient to give us a clear and distinct conception of God."

"The two operations of our understanding, intuition and deduction, on which alone we have said we must rely in the acquisition of knowledge."

"I resolved to feign that all the perceptions I had ever received were no truer than the illusions of my dreams."