In April 1874, thirty painters rejected by the official Salon held a show in the studio of the photographer Nadar. One Monet work was titled Impression, soleil levant — Impression, Sunrise.

The critic Louis Leroy sneered in the paper: ‘This thing is worth less than a wallpaper sketch, because that’s what an “impression” is.’ To everyone’s surprise, the painters pinned the insult to their chests like a medal — and the word ‘Impressionism’ was born.

What they did sounds obvious today, but was revolutionary then: leave the darkroom, carry the easel outdoors, record shifting light in quick strokes, paint shadows blue-violet (not black). They proved painting isn’t copying the object — it’s copying that one second of light.