Examine the life of the best and most productive men and nations, and ask yourselves whether a tree which is to grow proudly skywards can dispense with bad weather and storms. Whether misfortune and opposition, or every kind of hatred, jealousy, stubbornness, distrust, severity, greed, and violence do not belong to the favourable conditions without which a great growth even of virtue is hardly possible?

A bad conscience is easier to cope with than a bad reputation.

It is only those who know how to feel that "this is not good" who devise improvements.

Not with wrath do we kill, but with laughter. Come, let us kill the spirit of gravity!

Whereas the man of action binds his life to reason and its concepts so that he will not be swept away and lost, the scientific investigator builds his hut right next to the tower of science so that he will be able to work on it and to find shelter for himself beneath those bulwarks which presently exist.

When our brain feels too weak to deal with our opponent's objections, our heart answers by casting suspicion on their underlying motives.

Many are obstinate with regard to the pathway once they have set upon it, few with regard to the goal.