The greatest tragedy in mankind's entire history may be the hijacking of morality by religion.

As our own species is in the process of proving, one cannot have superior science and inferior morals. The combination is unstable and self-destroying.

Sometimes I think we're alone in the universe, and sometimes I think we're not. In either case the idea is quite staggering.

My favourite definition of 'Intellectual' is: 'A person whose education surpasses their intelligence.'

I'm sure the universe is full of intelligent life. It's just been too intelligent to come here.

There is hopeful symbolism in the fact that flags do not wave in a vacuum.

Science can destroy religion by ignoring it as well as by disproving its tenets. No one ever demonstrated, so far as I am aware, the non-existence of Zeus or Thor— but they have few followers now.

Any teacher that can be replaced by a machine should be!

If we have learned one thing from the history of invention and discovery, it is that, in the long run - and often in the short one - the most daring prophecies seem laughably conservative.

This is the first age that's ever paid much attention to the future, which is a little ironic since we may not have one.

The intelligence of the planet is constant, and the population is growing.

The best measure of a man's honesty isn't his income tax return. It's the zero adjust on his bathroom scale.

I don't pretend we have all the answers. But the questions are certainly worth thinking about.

I don't believe in God but I'm very interested in her.

Any sufficiently advanced technology is indistinguishable from magic. Clarke's Third Law