We accumulate our opinions at an age when our understanding is at its weakest.

Doubt must be no more than vigilance, otherwise it can become dangerous.

There exists a species of transcendental ventriloquism by means of which men can be made to believe that something said on earth comes from Heaven.

He who is in love with himself has at least this advantage - he won't encounter many rivals.

Prejudices are so to speak the mechanical instincts of men: through their prejudices they do without any effort many things they would find too difficult to think through to the point of resolving to do them.