Progress isn't made by early risers. It's made by lazy men trying to find easier ways to do something.

Selfishness is the bedrock on which all moral behavior starts and it can be immoral only when it conflicts with a higher moral imperative.

Daughters can spend ten percent more than a man can make in any usual occupation. That’s a law of nature, to be known henceforth as ‘Harshaw’s Law.

Remember this: once the human race is established on more than one planet and especially, in more than one solar system, there is no way now imaginable to kill off the human race.

All my enemies are self-appointed.

Duty is a debt you owe to yourself to fulfill obligations you have assumed voluntarily.

Of all the strange 'crimes' that human beings have legislated out of nothing, 'blasphemy' is the most amazing -- with 'obscenity' and 'indecent exposure' fighting it out for second and third place.