The double portrait of Federico da Montefeltro and Battista Sforza by Piero della Francesca in the Uffizi Gallery, Florence, is an intriguing masterpiece by one of the greatest painters of the Italian Renaissance. Most familiar to art lovers are its superb profile portraits of two notable early Renaissance personages. But it also comprises, on the back of the portrait panels, uniquely captivating allegorical scenes, representing each of them in a triumphal procession, above a simulated parapet bearing a Latin inscription. Though now displayed in a rigid modern frame, the work was originally designed as a portable folding diptych (two-panel painting), hinged to fold with the allegorical scenes on the outside. Thus it was no doubt intended for intimate personal reflection rather than for public display. Despite the diptych’s artistic quality and distinctive content, no documents have as yet shed light on its genesis. Since Federico was a highly erudite patron …