Jim Draper: This big marble is by Jean-Baptiste Carpeaux, after he had won the Rome prize that was the goal of every ambitious French sculptor, which took a young artist to Rome to study from the antique. The energy and study that Carpeaux put into this is absolutely extraordinary. This evolved over about five years, and so he had many occasions to consult human bodies to get them into this writhing mass.

We know until the very last minute, he was hiring new models. He even put up a family of Roman models at his own expense, feeding and housing them, to help him work this through. The precise nature of every single muscle—and, boy, does he know about muscles and bones—the clenched feet of Ugolino, and the tendons just practically ripping in the bent legs. So real study of human beings, but total respect for the past. It's this kind of dense research into the subject that makes this the masterpiece that it is.