These long chains of perfectly simple and easy reasonings by means of which geometers are accustomed to carry out their most difficult demonstrations had led me to fancy that everything that can fall under human knowledge forms a similar sequence; and that so long as we avoid accepting as true what is not so, and always preserve the right order of deduction of one thing from another, there can be nothing too remote to be reached in the end, or to well hidden to be discovered.

Archimedes, that he might transport the entire globe ... demanded only a point that was firm and immovable; so also, I shall be entitled to entertain the highest expectations, if I am fortunate enough to discover only one thing that is certain and indubitable.

If I go for the alternative which is false, then obviously I shall be in error; if I take the other side, then it is by... chance that I arrive at the truth, and I shall still be at fault.... In this incorrect use of free will may be found the privation which constitutes the essence of error.

We never understand a thing so well,and make it our own, as when we have discovered it for ourselves.

There is a little gland in the brain in which the soul exercises its functions in a more particular way than in the other parts.

Your joy is your sorrow unmasked. And the self-same well from which your laughter rises was often-times filled with your tears.

The senses deceive from time to time, and it is prudent never to trust wholly those who have deceived us even once.