This small, hazy view of the harbour of Le Havre at dawn is the painting that gave a whole art movement its name.

Monet showed it in 1874 at an independent exhibition in Paris organised by artists who had been rejected by the official Salon. A critic, Louis Leroy, mocked the title in a satirical review, sneering that it was just an "impression" — and called the whole group "Impressionists". The insult stuck, and the artists eventually adopted it.

Look at the sun: a small disc of orange, almost the same brightness as the grey sky around it. In black and white, it practically disappears. Monet wasn't painting objects. He was painting a moment of light that would be gone in minutes.