It’s not hard to find, among the leafy swords and demented purple flags, the single white iris (perhaps a stand-in for the artist) that restores order to the restive mass of flowers that spill across the canvas of the garden.

Against the wall of the Saint-Paul Hospital, there’s an absence of colour in the iris, apart from its delicate golden throat and the red river earth in which it grows.

Only a few paces, and Van Gogh steps into the bright, cheerful garden. Only a few brushstrokes and the flower is captured.