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.

If ... it is not in my power to arrive at the knowledge of any truth, I may at least do what is in my power, namely, suspend judgement ...

When any one has offended me, I try to raise my soul so high that the offense cannot reach it.

My first rule was to accept nothing as true which I did not clearly recognize to be so; to accept nothing more than what was presented to my mind so clearly and distinctly that I could have no occasion to doubt it. The second rule was to divide each problem or difficulty into as many parts as possible. The third rule was to commence my reflections with objects which were the simplest and easiest to understand, and rise thence, little by little, to knowledge of the most complex. The fourth rule was to make enumerations so complete, and reviews so general, that I should be certain to have omitted nothing.

Conquer yourself rather than the world.

I think, therefore I am.