Sculpture, according to Clement Greenberg, lagged behind painting in ridding itself of things not intrinsic to its medium, partly because of its literal presence. Because it had less to discard, painting, he believed, led the way in jettisoning the inessential. This may explain why, at least until David Smith hit his stride, so many of the most exciting, inventive modern works in three-dimensions were made not by sculptors, but by painters. Liberated, perhaps, by their lack of conventional ideas about what a sculpture could or should be, painters such as Edgar Degas, Pablo Picasso, and Henri Matisse created an “alternative tradition” of forward-looking sculpture as compelling and unexpected as any of their works on canvas or paper—and sometimes even more so. (Yes, I’m aware of the sculptor Julí González’s important role in the evolution of modernist construction, but even his initial rethinkings of the nature of three-dimensional form date from his close collaboration with his painter friend, Picasso.) It’s a truism that to appreciate sculpture fully we have to experience it in the flesh. Notoriously unreliable for works in two dimensions, reproductions are even more inadequate when the most crucial issue is how a work claims space and develops in the round.

Over the past decade and a half, it has been fairly easy for sculpture enthusiasts to have direct encounters with examples of the “alternative tradition,” particularly with the work of Degas and Picasso, although doing so has sometimes required good timing, a certain amount of effort,