Vitale da Bologna: Adam and Eve, Cain and Abel
Abbey of Pomposa, Italy
The scene on the left follows the traditional iconography with two interesting exceptions: the serpent is itself indulging in the fruit, and the primal couple are seated. Other features are at least as old as the 4th century: the tree with fruit in its somewhat round crown; the couple being on either side of it, with Adam on the left; the snake coiling around the trunk; Eve's passing a fruit to Adam; and the couple's nakedness.
The two Cain and Abel scenes follow Genesis 4 straightforwardly.
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More of Adam and Eve
More of Cain and Abel
Photographed at the abbey by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.