Any system which allows men to choose their own future will end by choosing safety and mediocrity, and in such a Reality the stars are out of reach.

Surely no child, and few adults, have ever watched a bird in flight without envy.

Do not forget that a traitor within our ranks, known to us, can do more harm to the enemy than a loyal man can do good to us.

He had read much, if one considers his long life; but his contemplation was much more than his reading. He was wont to say that if he had read as much as other men he should have known no more than other men.

The saddest aspect of life right now is that science gathers knowledge faster than society gathers wisdom.

A robot must protect its own existence as long as such protection does not conflict with the First or Second Laws.

Science can amuse and fascinate us all, but it is engineering that changes the world.