In 1916, a trainee doctor befriended a wounded young soldier in a hospital in Nantes. André Breton was working in the neurological ward and reading Freud. Jacques Vaché was a war interpreter, moving across the front between the Allied positions and disrupting where he could; he once collected cast-off uniforms from different armies, including enemy forces, and sewed them together to make his own “neutral” costume. He sent Breton letters describing his “comatose apathy” and indifference to the conflict, though, he wrote, “I object to dying in wartime”.

Weeks after the Armistice, Vaché killed himself in a hotel room. Breton hailed him “the deserter from within” and one of the key inspirations for “The Surrealist Manifesto”, published in Paris in 1924.

This slim volume turned out to be the most influential artistic pronouncement of the century. Breton argued that rational realpolitik had created the catastrophe of the first world war. Championing the irrational, the subconscious, dream states — “pure psychic automatism” — he called for a revolution of the mind: “thought dictated in the absence of all control exercised by reason.”