This Is Not an Introduction
During World War I, several artists coped with a world that had seemingly rejected logic and reason by creating art that embraced nonsense and irrationality. Dada, as this movement was called, strove to strip words and images of meanings. An installation titled Fountain is really a porcelain urinal. A poem titled Karawane, (caravan), is really just a sequence of nonsense sounds.
As the world returned to sanity following the Great War, Dada gave rise to Surrealism, which preserved the nonsense but turned it into the nonsense of dreams and then made an effort to reconcile it with the reality of our waking lives. Think: Salvador Dalí's La persistència de la memòria, (The Persistence of Memory), also known as “that painting with the melting clocks”.
One of the great surrealist painters was Belgian René Magritte. You're probably familiar with several of his works, such as Golconda, (also known as “a bunch of guys standing around in midair”), and The Son of Man (also known as “that picture from The Thomas Crown Affair”).
My favorite of Magritte's works, though, is The Treachery of Images. It is a very simple picture, just a realistic drawing of a pipe with “this is not a pipe” written beneath in French. Like a lot of Dadaist and Surrealist art, it left many people confused and angry. Of course it was a pipe! Just look at it!
Responding to the furor later, Magritte said “The famous pipe. How people reproached me for it! And yet, could you stuff my pipe? No, it's just a representation, is it not? So if I had written on my picture 'This is a pipe', I'd have been lying!”