Glory of St. Euphemia
Sant'Eufemia Church, Giudecca, Venice
Euphemia was a martyr and holds her martyr's palm as she ascends to Heaven in this image, but the scene portrayed is not her martyrdom. The person being slain on the steps reaches up with his fingers folded in the Trinitarian blessing configuration in which the index and middle fingers represent the two distinct natures of Christ: human and divine. At the Council of Chalcedon, held in St. Euphemia's church in that city in 451, the Church promulgated the doctrine that the two natures "were united in one person, but so that each nature acted according to its own qualities and characteristics" (Catholic Encyclopedia, s.v. "Council of Chalcedon").
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Source: this page at Wikimedia Commons.