The moon is the first milestone on the road to the stars.

Human judges can show mercy. But against the laws of nature, there is no appeal.

We have to abandon the idea that schooling is something restricted to youth. How can it be, in a world where half the things a man knows at 20 are no longer true at 40 - and half the things he knows at 40 hadn't been discovered when he was 20?

Now, before you make a movie, you have to have a script, and before you have a script, you have to have a story; though some avant-garde directors have tried to dispense with the latter item, you'll find their work only at art theaters.

Now I'm a scientific expert; that means I know nothing about absolutely everything.

The crossing of space ... may do much to turn men's minds outwards and away from their present tribal squabbles. In this sense, the rocket, far from being one of the destroyers of civilisation, may provide the safety-value that is needed to preserve it.

1. When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong. 2. The only way of discovering the limits of the possible is to venture a little way past them into the impossible. 3. Any sufficiently advanced technology is indistinguishable from magic.