It is not enough to have a good mind. The main thing is to use it well.

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 th eincreasing discovery of my own ignorance

These long chains of perfectly simple and easy reasonings by means of which geometers are accustomed to carry out their most difficult demonstrations had led me to fancy that everything that can fall under human knowledge forms a similar sequence; and that so long as we avoid accepting as true what is not so, and always preserve the right order of deduction of one thing from another, there can be nothing too remote to be reached in the end, or to well hidden to be discovered.

I am accustomed to sleep and in my dreams to imagine the same things that lunatics imagine when awake.

It's the familiar love-hate syndrome of seduction: "I don't really care what it is I say, I care only that you like it."

It is not enough to have a good mind. The main thing is to use it well.

For how do we know that the thoughts which occur in dreaming are false rather than those others which we experience when awake, since the former are often not less vivid and distinct than the latter?