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

“In order to seek truth, it is necessary once in the course of our life to doubt, as far as possible, of all things.”

“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.”

“Each problem that I solved became a rule which served afterwards to solve other problems”

“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.”

“I am thing that thinks: that is, a things that doubts,affirms, denies, understands a few things, is ignorant of many things, is willing, is unwilling, and also which imagines and has sensory perceptions.”

“For I found myself embarrassed with so many doubts and errors that it seemed to me that the effort to instruct myself had no effect other than the increasing discovery of my own ignorance”