It’s a long-established fact of art history that Pablo Picasso, trained only as a painter, revolutionized sculpture in the twentieth century. He introduced new subjects, such as still life; new materials, using sheet metal in the 1914 Guitar and everyday objects like a bicycle seat and handlebars for the 1942 Bull’s Head; new processes such as assemblage, used to make the Cubist works of the teens; new vocabularies, such as the “drawing in space,” openwork constructions of welded iron rods, in the project for a monument to the poet and critic Guillaume Apollinaire in the late 1920s.

He made space an equal partner to mass and form. And he even managed to nudge two ancient and venerable modes, the wheel-turned pot and modelled monolith, into new and unexpected directions. In the latter case, this was a hybrid form, the monolith-assemblage, that resulted when Picasso pushed his exploration of his paramour Marie-Thérèse Walter’s head so far in one of the Boisgeloup portraits of the 1930s that it devolved into four separate components.

Prior to “Picasso Sculpture,” the Museum of Modern Art’s sweeping survey, there hadn’t been a Picasso sculpture retrospective since 1966, seven years before the artist’s death.1Until then little had been known about Picasso’s activity as a sculptor. He kept almost all of his work to himself and rarely showed it. Not until the opening of the Musée Picasso in Paris in 1985, its collections comprised of works formerly in the artist’s possession,