If once you forfeit the confidence of your fellow-citizens, you can never regain their respect and esteem.

One of the greatest features of science is that it doesn't matter where you were born, and it doesn't matter what the belief systems of your parents might have been: If you perform the same experiment that someone else did, at a different time and place, you'll get the same result.

Plato is my friend; Aristotle is my friend, but my greatest friend is truth.

If you can't explain it simply, you don't understand it well enough.

We're living in primate heaven. We're warm, dry, we're not hungry, we don't have fleas and ticks and infections. So why are we so miserable?