I find it as difficult to understand a scientist who does not acknowledge the presence of a superior rationality behind the existence of the universe as it is to comprehend a theologian who would deny the advances of science.

I believe in an immortal soul. Science has proved that nothing disintegrates into nothingness. Life and soul, therefore, cannot disintegrate into nothingness, and so are immortal.

If we continue at this leisurly pace, we will have to pass Russian customs when we land on the moon.

The rocket worked perfectly, except for landing on the wrong planet.

Don't tell me that man doesn't belong out there. Man belongs wherever he wants to go - and he'll do plenty well when he gets there.

There are flying grandfathers. But I intend to be an orbiting grandfather.

One good test is worth a thousand expert opinions.