(JNS) — Until recently, French Impressionism was a Cinderella story. Derided in the late 19th century and excluded from the French academy (Salon), Impressionism—whose name derives from a critic’s mockery—became one of the most beloved art movements.

Impressionist sections are among the most trafficked in art museums, whose gift shops hawk umbrellas, tote bags, ballpoint pens and other accessories decorated with works by Claude Monet, Auguste Renoir, Edgar Degas, Paul Cézanne, Camille Pissarro and others. Those artists’ fortunes rose so much that it became a mark of academic connoisseurship to...