The treatise Skala (κλίμαξ, 'steep staircase') or Ladder of Divine Ascent was written by St Ioannis Climacus, probably in the 7th century. It is a masterpiece of Byzantine Christianity, which continues to be read by monks as an important reference. In the Monastery's fresco, St John, at the lower right, shows a tall and steep staircase that reaches up to heaven to a crowd of monks who follow him. Monks are climbing with effort, troubled by demons, and many fall from various heights. The monks who fall end up in the mouth of the Dragon, a representation of Satan, horrible and impressively designed with perspective, who is lurking beneath the ladder.
