As the third son of John II, a King of France who reigned from 1350 to 1364, Jean, the Duke of Berry, had a treasure chest of disposable income, which never hurts. But he had something more important than money—incredible taste. Around 1410, the Duke commissioned an object that is a splendor of human history, recently described by the Financial Times as the “world’s most beautiful book.” At the Château de Chantilly, the book’s luminous pages have been removed from their bindings so that its 121 illustrations can be viewed panoramically. Created for the prayer book Les Très Riches Heures, these miniature artworks are dazzling celebrations of earthly existence. —Nicholas Fox Weber