For most of his life, Henri Rousseau was a tax collector. His nickname was “Le Douanier” (the customs officer). During his painting career, which began seriously in his middle years, Rousseau was characterized by critics as naïve and uneducated. After retiring, he supplemented his pension by playing violin, for which he’d won awards as a schoolboy, in the streets of Montparnasse. Rousseau is recognized as a self-taught master, and yet he’s little understood. “The Ambition of Painting” is part of a wider technical study of the artist’s canvases, conducted by the Barnes Foundation in Philadelphia, that focuses on the mechanics of his art. Between 2021 and 2024, five underlying paintings and eight reworked compositions have been discovered, and five paintings have been re-dated. Featuring around 50 works—including The Snake Charmer and The Sleeping Gypsy—this show is a joint collaboration between the Musée de l’Orangerie and the Barnes Foundation. —Jimmy Lux Fox