Whatever I have up till now accepted as most true and assured I have gotten either from the senses or through the senses. But from time to time I have found that the senses deceive, and it is prudent never to trust completely those who have deceived us even once.

Divide each difficulty into as many parts as is feasible and necessary to resolve it.

The entire method consists in the order and arrangement of the things to which the mind's eye must turn so that we can discover some truth.

I know that I exist; the question is, What is this 'I' that 'I' know.

Neither divine grace nor natural knowledge ever diminishes freedom.

Some years ago I was struck by the large number of falsehoods that I had accepted as true in my childhood, and by the highly doubtful nature of the whole edifice that I had subsequently based on them. I realized that it was necessary, once in the course of my life, to demolish everything completely and start again right from the foundations if I wanted to establish anything at all in the sciences that was stable and likely to last.

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.