I am indeed amazed when I consider how weak my mind is and how prone to error.
I accept no principles of physics which are not also accepted in mathematics.
Travelling is almost like talking with those of other centuries.
Except our own thoughts, there is nothing absolutely in our power.
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
The reading of all good books is indeed like a conversation with the noblest men of past centuries who were the authors of them, nay a carefully studied conversation, in which they reveal to us none but the best of their thoughts.