When conscious activity is wholly concentrated on some one definite purpose, the ultimate result, for most people, is lack of balance accompanied by some form of nervous disorder.

There are three ways of securing a society that shall be stable as regards population. The first is that of birth control, the second that of infanticide or really destructive wars, and the third that of general misery except for a powerful minority.

Science is what we know, and philosophy is what we don't know.

I consider the official Catholic attitude on divorce, birth control, and censorship exceedingly dangerous to mankind.

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

The scientific attitude of mind involves a sweeping away of all other desires in the interest of the desire to know.

All serious innovation is only rendered possible by some accident enabling unpopular persons to survive.