Young and beardless, John is absorbed in reading a volumen (scroll). The eagle presents him with a phylactery, a symbol of inspiration, whispering what he is to write.
John's right leg was discovered in the central embankment of the cloister site on June 26, 1973.
The association between John and the eagle is based on the bird's supposed ability to face the sunlight directly, paralleling John’s testimony of the divinity of Christ.