The only secure knowledge is that I exist.

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

Wonder is the first of all the passions.

The two operations of our understanding, intuition and deduction, on which alone we have said we must rely in the acquisition of knowledge.

Even those who have the weakest souls could acquire absolute mastery over all their passions if we employed sufficient ingenuity in training and guiding them.

Travelling is almost like talking with those of other centuries.

There is nothing so far removed from us as to be beyond our reach, or so hidden that we cannot discover it.