The Ten Commandments should be headed like an examination paper: No more than six to be attempted.

The satisfaction to be derived from success in a great constructive enterprise is one of the most massive that life has to offer.

If a Black Death could be spread throughout the world once in every generation survivors could procreate freely without making the world too full.

Of course not. After all, I may be wrong.

Many a man will have the courage to die gallantly, but will not have the courage to say, or even to think, that the cause for which he is asked to die is an unworthy one.

As men begin to grow civilized, they cease to be satisfied with mere taboos.

All that passes for knowledge can be arranged in a hierarchy of degrees of certainty, with arithmetic and the facts of perception at the top.