This work comes from a series of eighty biblical watercolors that Blake made for Thomas Butts, an important patron. He found the subject in chapter 10 of the book of Revelation and describes both the author and his vision. A diminutive Saint John, pen in hand, on the island of Patmos, gazes at a "mighty angel . . . clothed with a cloud . . . a rainbow was upon his head, and his face was as it were the sun, and his feet as pillars of fire." The artist based the angel's water-spanning stance on prints of the ancient Colossus of Rhodes and envisioned the seven thunders described in the text as horsemen riding through clouds.