The trouble with the world is that the stupid are cocksure and the intelligent are full of doubt.

I respect faith, but doubt is what gets you an education.

Just think of the tragedy of teaching children not to doubt.

Our doubts are traitors And make us lose the good we oft might win By fearing to attempt.

I am plagued by doubts. What if everything is an illusion and nothing exists? In that case, I definitely overpaid for my carpet. If only God would give me some clear sign! Like making a large deposit in my name at a Swiss bank.

A proof tells us where to concentrate our doubts.

The only thing I don't doubt is my doubt.

If a man will begin with certainties he shall end in doubts; but if he will be content to begin with doubts he shall end in certainties.

Doubt makes the mountain which faith can move.

If a man will begin with certainties, he shall end in doubts; but if he will be content to begin with doubts, he shall end in certainties.