You may well ask me why...I took the time to write [books]. I can only reply that I do not know. There was no why about it. I had to: that was all.

Choose silence of all virtues, for by it you hear other men's imperfections, and conceal your own.

The longer I live, the more I realize that I am never wrong about anything, and that all the pains I have so humbly taken to verify my notions have only wasted my time!

All sorts of bodily diseases are produced by half-used minds.

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.

I fought linotype and montype for some time because it would not justify as well as handset could be made to do; but at last, as always happens, the machine outdid the hand, and got all the best types on it.

The devil can quote Shakespeare for his own purpose.