You do not settle whether an argument is justified by merely showing that it is of some use. The distinction is not between useful and useless experiments but between barbarous and civilized behaviour. Vivisection is a social evil because if it advances human knowledge, it does so at the expense of human character.

The fact that a believer is happier than a skeptic is no more to the point than the fact that a drunken man is happier than a sober one.

We are made wise not by the recollection of our past, but by the responsibility for our future.

The sound body is the product of the sound mind.

Even to this day it is easier than it ought to be for me to get a rise out of an American by telling him something about himself which is equally true about every human being on the face of the globe. He at once resents this as a disparagement and an assertion on my part that people in other parts of the globe are not like that, and are loftily superior to such weaknesses.

Nature holds no brief for the human experiment; it must stand or fall by its results.

I like to quote myself frequently and often, it makes me sound much more intelligent than I actually am.