I have great faith in optimism as a guiding principle, if only because it offers us the opportunity of creating a self-fulfilling prophecy.

Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying.

The entire sweep of human history from the dark ages into the unknown future was considerably less important at the moment than the question of a certain girl and her feelings toward him.

The universe must be full of voices, calling from star to star in a myriad tongues. One day we shall join that cosmic conversation.

It is vital to remember that information - in the sense of raw data - is not knowledge, that knowledge is not wisdom, and that wisdom is not foresight. But information is the first essential step to all of these.

Astronomy, as nothing else can do, teaches men humility.

They had not yet attained the stupefying boredom of omnipotence; their experiments did not always succeed.