This is a scene from the life of St Agnes, based on William Caxton’s fifteenth-century Golden Legend. At the age of thirteen Agnes rejected marriage and dedicated her life to God. She refused to renounce her vow of chastity and was stripped of her clothes and taken to a brothel. She prayed for divine intervention and her room was filled by a miraculous light. Her hair grew long, and a white robe appeared before her. This is the moment shown here by Cowper.