If an elderly but distinguished scientist says that something is possible, he is almost certainly right; but if he says that it is impossible, he is very probably wrong.

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

The limits of the possible can only be defined by going beyond them into the impossible.

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

The only way to discover the limits of the possible is to go beyond them into the impossible.

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

None is richer than he who simply has peace of mind.

I refuse to answer that question on the grounds that I don't know the answer.

Some people want it to happen, some wish it would happen, others make it happen.

Whatever it is you're seeking won't come in the form you're expecting.

Action without study fatal. Study without action is futile.

Human relations are built on feeling, not on reason or knowledge. And feeling is not an exact science; like all spiritual qualities, it has the vagueness of greatness about it.

Age is a question of mind over matter. If you don’t mind, it doesn’t matter.

You can never get a cup of tea large enough or a book long enough to suit me.

I warn you that when the princes of this world start loving you it means they are going to grind you up into battle sausage.