An open mind is all very well in its way, but it ought not to be so open that there is no keeping anything in or out of it.

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.

Seek simplicity, and distrust it.

The art of progress is to preserve order amid change and to preserve change amid order.

Science repudiates philosophy. In other words, it has never cared to justify its truth or explain its meaning.

After you understand about the sun and the stars and the rotation of the earth, you may still miss the radiance of the sunset.

Almost all new ideas have a certain aspect of foolishness when they are first produced.