The two foes of human happiness are pain and boredom.

• 

  What moves man is the striving to exist; but when his existence is assured, he knows not what to do with it.

• 

  Life swings like a pendulum backward and forward between pain and boredom.

• 

  To estimate how happy a man is, one should ask not what pleases him, but what troubles him.

• 

  Solitude is the lot of all outstanding minds.

• 

  What a man is in himself, what accompanies him when he is alone, what no one can give or take away, is more essential to him than everything he has or what he may be in the eyes of others.

• 

  The life of every individual, if we survey it as a whole and bring out only its most significant features, is really always a tragedy; but gone through in detail, it has the character of a comedy.

All quotes