Mademoiselle Yvonne Landsberg

The sittings ran through the summer of 1914, in a Paris that was weeks away from war. Yvonne Landsberg was about 18, from a Brazilian family living in the city, and her brother had asked Matisse for a portrait of her. Matisse agreed on one condition, that after a first conventional drawing he could paint her as he liked.

He scraped the canvas back and began again at almost every session, and she grew harder to recognise each time. At the last one he turned the brush around and cut wide curving arcs into the wet paint with the wooden end, lines that open outward from her shoulders and hips like a flower coming out. The ridges of paint they pushed aside were never smoothed down, so the marks are still physically there.

The Landsbergs declined to buy it. It went eventually to the American collectors Louise and Walter Arensberg, whose collection came to Philadelphia in 1950.