The Joke is the name of a book published by Milan Kundera in 1967, the year before the so-called Prague Spring.
As communist censorship slackened in Czechoslovakia, its arts-scene exploded with color; the 5-year period leading up to the Soviet intervention of 1968 was a sort of golden age for film, literature, and photography. Kundera's The Joke is representative of the comparative freedom of the era, as it was considered by many to be a scathing criticism of communism in the sheep's clothing of a love story.
At one point, Kundera's protagonist comments: "Optimism is the opium of the people."
...When someone described The Joke as "a major indictment of Stalinism," Kundera responded, "Spare me your Stalinism, please. The Joke is a love story." Nonetheless, this book established Kundera as a vitriolic and graceful opponent of the communist regime.
In June of 1967, as the censoring Soviet hand strengthened once more its grip on the throat of the Czechoslovakian art world, Kundera addressed the Fourth Congress of the Union of Czechoslovak writers, proclaiming that "culture is a more significant sphere of endeavor than politics."
Italicized quote from Gale Stokes' From Stalinism to Pluralism.