My third maxim was to try always to conquer myself rather than fortune, and to change my desires rather than the order of the world, and generally to accustom myself to believing that there is nothing entirely in our power except our thoughts, so that after we have done our best regarding things external to us, everything in which we do not succeed is for us absolutely impossible.

And I shall always hold myself more obliged to those by whose favour I enjoy uninterrupted leisure than to any who might offer me the most honourable positions in the world.

Each problem that I solved became a rule, which served afterwards to solve other problems.

Truths are more likely to be discovered by one man than by a nation

Few look for truth; many prowl about for a reputation of profundity by arrogantly challenging whichever arguments are the best.

Nothing comes out of nothing.

I can doubt everything, except one thing, and that is the very fact that I doubt. Simply put - I think, therefore I am