The first precept was never to accept a thing as true until I knew it as such without a single doubt.

The greatest minds are capable of the greatest vices as well as of the greatest virtues.

I desire to live in peace and to continue the life I have begun under the motto 'to live well you must live unseen

You just keep pushing. You just keep pushing. I made every mistake that could be made. But I just kept pushing.

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.

If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things.

Everything is self-evident.