"In his 1968 novel, The Joke, the Czech writer Milan Kundera has a character send a postcard bearing the line "Optimism is the opium of the people," for which the character is accused of being an enemy of the people and sentenced to hard labor in the coal mines".
from Bright-sided: How the Relentless Promotion of Positive Thinking Has Undermined America [e pure l'Europa]
by Barbara Ehrenreich