Auguste Rodin— almost the last great figure sculptor—shares a rare distinction with history’s two greatest visual artists, Leonardo and Michelangelo: Like the Mona Lisa and Michelangelo’s (first) David, Rodin’s “Thinker” is ubiquitous; every person in the western world, no matter how uninterested in art, knows what it looks like. Like the Mona Lisa and the David, the Thinker is not its maker’s best work. Rodin is best known for his bronzes, but his best sculpture (according to me and a tiny, brave minority of critics) is in marble. He is a national icon of France, but his best work is not in the Musee Rodin or the Musee D’Orsay in Paris—it’s in the United States. Not in Philadelphia’s Rodin Museum, but in New York, at the Metropolitan Museum of Art.

There are two brilliant artworks named “Madame X” — and, actually, they’re both at the Met. The first is John Singer Sargent’s magnum opus, a painting of a lithe, white-skinned Mme. Virginie Gautreau in a tight black dress. Originally Sargent’s “Madame X” showed Madame Gautreau — belle of Paris in the 1880s — with the right shoulder-strap of her dress dangling at her side. The painting’s Salon debut was so scandalous that Sargent had to repaint Virginie’s strap so it was actually on her shoulder, to avoid her dress looking as if it were about to fall to the floor.