I did not imitate the skeptics who doubt only for doubting's sake, and pretend to be always undecided; on the contrary, my whole intention was to arrive at a certainty, and to dig away the drift and the sand until I reached the rock or the clay beneath.

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

So far, I have been a spectator in this theater which is the world, but I am now about to mount the stage, and I come forward masked.

Let whoever can do so deceive me, he will never bring it about that I am nothing, so long as I continue to think I am something.

To live without philosophizing is in truth the same as keeping the eyes closed without attempting to open them.

Now therefore, that my mind is free from all cares, and that I have obtained for myself assured leisure in peaceful solitude, I shall apply myself seriously and freely to the general destruction of all my former opinions.

In God there is an infinitude of things which I cannot comprehend, nor possibly even reach in any way by thought; for it is the nature of the infinite that my nature, which is finite and limited, should not comprehend it.