An important scientific innovation rarely makes its way by gradually winning over and converting its opponents: it rarely happens that Saul becomes Paul. What does happen is that its opponents gradually die out, and that the growing generation is familiarized with the ideas from the beginning: another instance of the fact that the future lies with the youth.

[Often paraphrased as "Science progresses one funeral at a time".]

Be excellent to each other, and party on!

The Puritan ethic is the constant fear that someone, somewhere, is having a good time.

An expert is a person who has found out by his own painful experience all the mistakes that one can make in a very narrow field.

We are all agreed that your theory is crazy. The question which divides us is whether it is crazy enough to have a chance of being correct. My own feeling is that it is not crazy enough.

I still have objections to the … beauty of quantum mechanics, but she is correct.

I don't want to abolish government. I simply want to reduce it to the size where I can drag it into the bathroom and drown it in the bathtub.

You have to have a heart to have an attack

Other than that, Mrs. Lincoln, how did you enjoy the play?

The influence of coffee in stimulating the genital organs is notorious.