by Juan Carreño de Miranda (1614-1685), a Spanish Baroque artist.
St. John was of a noble French family, but became a priest in order to serve others and live a holy life. At his first Mass, a vision appeared of an angel with his hands on the heads of a Christian and a Moorish prisoner. After much prayer (and a journey to Rome to consult with the Pope), he founded the Trinitarian order to bring relief to Christian slaves in the Islamic lands, and to ransom them if possible.
You can see the angel at the upper left in the painting.
Thanks. The Baroque was simply a wonderful time for the arts.