Athens National Library/Courtesy A. Dean McKenzie

No ordinary biography. Quill pen in hand, Mark the Evangelist composes his life of Jesus in a tenth-century illuminated Byzantine manuscript.

Mark’s image of the heavens tearing open derives in part from two Hebrew prophets, David Ulansey concludes. From Ezekiel 1:1, in which the prophet sees visions of God when the heavens part, Mark took the image of the heavens opening, while the notion of the heavens as a cloth or tent comes from Isaiah 40:22. Mark combined the two images into one: At two crucial moments in Jesus’ life—at his baptism and at his crucifixion—Mark says the heavens (or a symbol of the heavens) ripped apart.