This three-part altarpiece depicts the visionary experiences of the layman Chiarito del Voglia, who commissioned it in the 1340s. The central panel--executed in gilded gesso relief and showing the apostles receiving communion through narrow tubes emanating from Christ's navel--is most unusual in subject matter and medium.
The left wing displays scenes from Christ's Passion, the events leading up to his Crucifixion. In an unusual addition, three scenes below the main panel feature the bearded donor Chiarito participating in the Mass. In the central scene, he participates in the communion of the Apostles shown above by means of a tube that extends down to his mouth.
On the right wing in the bottom panel, Chiarito, seen standing alone, listens to a monk preaching to an audience. His powerful vision is made manifest in the scene above. He imagines the blood of Christ flowing down from the Trinity, shown in the top panel, to bathe the crowd below. Diagonal lines on the pulpit direct the viewer's eyes to the flowing blood.