The nature of matter, or body considered in general, consists not in its being something which is hard or heavy or coloured, or which affects the senses in any way, but simply in its being something which is extended in length, breadth and depth.

Desire awakens only to things that are thought possible.

An optimist may see a light where there is none, but why must the pessimist always run to blow it out?

At last I will devote myself sincerely and without reservation to the general demolition of my opinions.

He lives well who is well hidden.

I was convinced that our beliefs are based much more on custom and example than on any certain knowledge.

... regard this body as a machine which, having been made by the hand of God, is incomparably better ordered than any machine that can be devised by man, and contains in itself movements more wonderful than those in any machine. ... it is for all practical purposes impossible for a machine to have enough organs to make it act in all the contingencies of life in the way in which our reason makes us act.