"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 have never made any distinction between the sciences, but have always held that all are linked together, and that it is easier to learn them all at once than to learn one separately."

"I had rather be dead than live without philosophy."

"The power of judging well and of distinguishing the true from the false, which is properly what is called good sense or reason, is by nature equal in all men."

"I suppose therefore that all the things I see are false; I believe that none of those things ever existed which my fallacious memory represents to me; I consider that I possess no senses; I imagine th…"