I have always noticed that deeply and truly religious persons are fond of a joke, and I am suspicious of those who aren't.

The consequences of a plethora of half-digested theoretical knowledge are deplorable.

What the learned world tends to offer is one second-hand scrap of information illustrating ideas derived from another second-hand scrap of information. The second-handedness of the learned world is the secret of its mediocrity.

It is a safe rule to apply that, when a mathematical or philosophical author writes with a misty profundity, he is talking nonsense.

Fundamental progress has to do with the reinterpretation of basic ideas.

We think in generalities, but we live in detail.

The way in which the persecution of Galileo has been remembered is a tribute to the quiet commencement of the most intimate change in outlook which the human race had yet encountered. Since a babe was born in a manger, it may be doubted whether so great a thing has happened with so little stir