Science is uncertain.

Doubt is clearly a value in science. It is important to doubt and that the doubt is not a fearful thing, but a thing of great value.

If we will only allow that, as we progress, we remain unsure, we will leave opportunities for alternatives.

While I am describing to you how Nature works, you won't understand why Nature works that way. But you see, nobody understands that.

Physics is like sex: sure, it may give some practical results, but that's not why we do it.

You say you are a nameless man. You are not to your wife and to your child. You will not long remain so to your immediate colleagues if you can answer their simple questions when they come into your office. You are not nameless to me. Do not remain nameless to yourself — it is too sad a way to be. Know your place in the world and evaluate yourself fairly, not in terms of the naïve ideals of your own youth, nor in terms of what you erroneously imagine your teacher's ideals are.

I don't feel frightened by not knowing things.