What is courage? Courage is the willingness to risk failure...There is only one danger I find in life, and that, indeed, is a real one. You may take too many precautions.

We cannot say that if a child is badly nourished he will become a criminal. We must see what conclusion the child has drawn.

Every therapeutic cure, and still more, any awkward attempt to show the patient the truth, tears him from the cradle of his freedom from responsibility and must therefore reckon with the most vehement resistance.

In the company of friends, writers can discuss their books, economists the state of the economy, lawyers their latest cases, and businessmen their latest acquisitions, but mathematicians cannot discuss their mathematics at all. And the more profound their work, the less understandable it is.

Men of genius are admired, men of wealth are envied, men of power are feared; but only men of character are trusted.

Each generation has its few great mathematicians, and mathematics would not even notice the absence of the others. They are useful as teachers, and their research harms no one, but it is of no importance at all. A mathematician is great or he is nothing.

There is a courage of happiness as well as a courage of sorrow.