What is wanted is an air of boredom. If you are melancholy, it is because you lack something, because you have failed in something.
 Stendhal, The Red and the Black (1830). copy citation

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Author Stendhal
Source The Red and the Black
Topic boredom melancholy
Date 1830
Language English
Reference
Note Translated by Horace B. Samuel
Weblink https://en.wikisource.org/wiki/The_Red_and_the_Black

Context

“When the prince had finished his siege of Kehl, he said to Julien, "You look like a Trappist, you are carrying to excess that principle of gravity which I enjoined upon you in London* A melancholy manner cannot be good form. What is wanted is an air of boredom. If you are melancholy, it is because you lack something, because you have failed in something." "That means showing one's own inferiority; if, on the other hand you are bored, it is only what has made an unsuccessful attempt to please you, which is inferior. So realise, my dear friend, the enormity of your mistake."” source