In “Celestial Advertising”1, Villiers de l’Isle-Adam imagines a machine capable of projecting onto the night sky gigantic advertisements. His intention is not to glorify contemporary progress but on the contrary to expose the inanity of Progress. Totally dedicated to the use of ironic antiphrasis, Villier’s tale praises this contraption only to better mock the bourgeois positivism which sustains it. However, from these depths of Stupidity the ironist prompts the emergence of an absurdity whose comic nature seems to finally make the author himself smile. Real glee can be felt in the evocation of the slogans invented by the writer who diverts himself by renewing the meaningfulness of advertisements and names of constellations. The celestial vault becomes a pretext for semiotisation, its being turned into meaningful signs as absurd as it is fun.