“At last I will devote myself sincerely and without reservation to the general demolition of my opinions.”

“I had become aware, as early as my college days, that no opinion, however absurd and incredible can be imagined, that has not been held by one of the philosophers.”

“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”

“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.”

“The last rule was to make enumerations so complete, and reviews so comprehensive, that I should be certain of omitting nothing.”

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

“And thus, the actions of life often not allowing any delay, it is a truth very certain that, when it is not in our power to determine the most true opinions we ought to follow the most probable.”