From the exhibit description:
The Belles Heures (1405–1408/9) of Jean de Berry, a treasure of The Cloisters collection, is one of the most celebrated and lavishly illustrated manuscripts in this country. Because it is currently unbound, it is possible to exhibit all of its illuminated pages as individual leaves, a unique opportunity never to be repeated. The exhibition will elucidate the manuscript, its artists—the young Franco-Netherlandish Limbourg Brothers—and its patron, Jean de France, duc de Berry. A select group of precious objects from the same early fifteenth-century courtly milieu will place the manuscript in the context of the patronage of Jean de Berry and his royal family, the Valois.
A short video introducing the manuscript is available on the museum website.