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

Thus each truth discovered was a rule available in the discovery of subsequent ones.

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?

The chief cause of human errors is to be found in the prejudices picked up in childhood.

An optimist may see a light where there is none, but why must the pessimist always run to blow it out?

To live without philosophizing is in truth the same as keeping the eyes closed without attempting to open them.

I should consider that I know nothing about physics if I were able to explain only how things might be, and were unable to demonstrate that they could not be otherwise.