If Viola's depictions of emotional states with no objective correlative — emotional states for which the viewer has no external object or event to understand them by—are one feature of many of his works, another, which has come to the forefront, is his reference to medieval and classical depictions of emotion. Most immediately, his subdued Catherine's Room 2001, has many scenes by scene parallels with Andrea di Bartolo's 1393 St. Catherine of Siena Praying.
