Ambrogio di Baldese, St. John at the Latin Gate
Tempera and gold on wood panel
Pinacoteca Vaticana, Rome
This panel from a predella of the life of St. John pictures the attempt to put him to death in a cauldron of boiling oil. But, as Caxton's translation of the Golden Legend puts it, "he never felt harm ne pain, and without suffering any harm he issued out." In the 5th century Christians built the church of San Giovanni in Oleo ("St. John in Oil") on the spot near the Latin Gate where the ordeal took place.
Some paintings will have the title "Martyrdom of St. John" or show an angel bringing John the palm of martyrdom, as this one does, but the tradition is that John died of natural causes at an advanced age.
The question of age is treated inconsistently in the images of the oil ordeal. Some picture him with a long white beard, as here, but others have him quite young.
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More of St. John the Evangelist
Photographed at the Pinacoteca Vaticana by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.