Such is professional jealousy; a scientist will never show any kindness for a theory which he did not start himself.

We all do no end of feeling, and we mistake it for thinking. And out of it we get an aggregation which we consider a boon. Its name is public opinion. It is held in reverence. Some think it the voice of God.

If man had created man, he would be ashamed of his performance.

Man is kind enough when he is not excited by religion

Customs do not concern themselves with right or wrong or reason. But they have to be obeyed; one reasons all around them until he is tired, but he must not transgress them, it is sternly forbidden.

Courage is resistance to fear, mastery of fear-not absence of fear. Except a creature be part coward it is not a compliment to say it is brave; it is merely a loose application of the word. Consider the flea! - incomparably the bravest of all the creatures of God, if ignorance of fear were courage.

Never do wrong when people are looking.