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

A robot must obey the orders given it by human beings except where such orders would conflict with the First Law. [The Second Law of Robotics]

I made up my mind long ago to follow one cardinal rule in all my writing — to be clear.

Writing, to me, is simply thinking through my fingers.

Knowledge is indivisible. When people grow wise in one direction, they are sure to make it easier for themselves to grow wise in other directions as well. On the other hand, when they split up knowledge, concentrate on their own field, and scorn and ignore other fields, they grow less wise - even in their own field.

It was childish to feel disappointed, but childishness comes almost as naturally to a man as to a child.

There never can be a man so lost as one who is lost in the vast and intricate corridors of his own lonely mind, where none may reach and none may save.