““Is he then an unhappy man?”
Poirot said:
“So unhappy that he has forgotten what happiness means. So unhappy that he does not know he is unhappy.”
The nun said softly:
“Ah, a rich man…””

““Peace, simpleton!” said the Princess. “Though he said he was unhappy, it does not follow that he must be in love.””

“If any be unhappy, let him remember that he is unhappy by reason of himself alone. For God hath made man to enjoy felicity and constancy of good.”

“The happiness and unhappiness of the rational, social animal depends not on what he feels but on what he does; just as his virtue and vice consist not in feeling but in doing.”

“As my mom has said, when one person is unhappy, it usually means two people are unhappy but that one has not come to terms with it yet.”

“The Outsider is always unhappy, but he is an agent that ensures the happiness for millions of 'Insiders.”

“He who does wrong is more unhappy than he who suffers wrong.”

“I'm like a starving man who has been given food. Maybe he's cold, and his clothes are torn, and he's ashamed, but he's not unhappy.”

“A man of action forced into a state of thought is unhappy until he can get out of it.”

“Then he thought himself unhappy, but happiness was all in the future; now he felt that the best happiness was already in the past.”