If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things.

It is only prudent never to place complete confidence in that by which we have even once been deceived.

—Rene Descartes

The first precept was never to accept a thing as true until I knew it as such without a single doubt.

—Rene Descartes

It is not enough to have a good mind. The main thing is to use it well.

—Rene Descartes

I think; therefore I am.

—Rene Descartes

It is not enough to have a good mind; the main thing is to use it well.

—Rene Descartes

Beliefs are what divide people. Doubt unites them.

—Peter Ustinov

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

—Clarence Darrow

Doubt whom you will, but never yourself.

—Christine Bovee

The whole problem with the world is that fools and fanatics are always so certain of themselves, but wiser people so full of doubts.

—Bertrand Russell

I think we ought always to entertain our opinions with some measure of doubt. I shouldn't wish people dogmatically to believe any philosophy, not even mine.

—Bertrand Russell