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.

People who think they know everything are a great annoyance to those of us who do.

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

When stupidity is considered patriotism, it is unsafe to be intelligent.

So the universe is not quite as you thought it was. You'd better rearrange your beliefs, then. Because you certainly can't rearrange the universe.

In life, unlike chess, the game continues after checkmate.

People think of education as something that they can finish.

There are no nations! There is only humanity. And if we don't come to understand that right soon, there will be no nations, because there will be no humanity.

A robot may not injure a human being, or, through inaction, allow a human being to come to harm.

Violence is the last refuge of the incompetent.

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

My heart knows what my mind only think it knows.

Virtue comes by nature, learning, and practice, and thanks to virtue, all of the aforesaid may deserve approval.

The abandoned infant's cry is rage, not fear.

He who thus considers things in their first growth and origin ... will obtain the clearest view of them.

What I do is put mirrors in the right place to reflect an image.

I write about what I know and also what I don't understand. Emotions for what has transpired.

It is more difficult to stay on top than to get there.

Look at the choices you have, not the choices that have been taken away from you. In them, there are whole worlds of strength and new ways to look at things.

Greatness as a leader is measured in part by your willingness to accept daunting challenges. Achieving tough goals requires practicing the secret of commitment: Risk all to win all.

Those who prepare for war get it.