(from top to bottom) Misericordia Polyptych [Madonna della Misericordia]. Piero della Francesca. 1460-62. Pinacoteca Comunale, Sansepolcro. This painting contains a self-portrait of the artist, third from the left, kneeling at the feet of Mary; Madonna of Mercy. Sano di Pietro. ca. 1440. Private collection; Madonna of the Franciscans. Duccio di Buoninsegna. 1280. Pinacoteca Nazionale, Siena. A polyptych [Greek poluptukha/having many folds] is a work of art composed of multiple panels, usually four or more. Diptych refers to two paneled pieces and triptych refers to those with three.
The Madonna della Misericordia or Virgin of Mercy is a traditional motif in Christian art which displays the Virgin Mary with an outstretched mantle. In the image, she uses her mantle to protect her worshippers. Artwork commissions with this theme were often made by groups [e.g., families, convents, guilds] who then were incorporated into the piece. Usually, the group is represented kneeling and of a smaller scale than the Madonna. Martin Luther scorned the image, likening it to "a hen with her chicks".
The oldest extant version is a small 13th Century piece by Duccio. The most famous example is The Madonna della Misericordia or The Polyptych of Misericordia, an altarpiece by Piero della Francesca in the Pinacoteca Comunale of Sansepolcro. Here Francesca features the Madonna as the centerpiece of the polyptych, flanked by the Virgin of the Annunciation, various saints, and images of the life of Christ. The piece was commissioned in 1445 by the Compagnia della Misericordia and was completed in 1462.