After years of finding mathematics easy, I finally reached integral calculus and came up against a barrier. I realized that this was as far as I could go, and to this day I have never successfully gone beyond it in any but the most superficial way.

What lasts in the reader's mind is not the phrase but the effect the phrase created: laughter, tears, pain, joy. If the phrase is not affecting the reader, what's it doing there? Make it do its job or cut it without mercy or remorse.

Tens of millions of Americans who neither know or understand the actual arguments for, or even against, evolution, march in the Army of the Night with their Bibles held high

As artists and traders in medieval cities began to form organizations, they instituted tough initiation ceremonies. Journeymen in Bergen, Norway, were shoved down a chimney, thrown three times into the sea, and soundly whipped. Such rites made belonging to the guild or corporation more precious to those who were accepted, and survived.

Intuition is the art, peculiar to the human mind, of working out the correct answer from data that is, in itself, incomplete or even, perhaps, misleading.

The intelligent man is never bored.

Modern science fiction is the only form of literature that consistently considers the nature of the changes that face us.