In the 5th century, a man named Palladius wrote the story of Valens, a monastic from Palestine. Valens was a well regarded monastic whose fervor for discipline had won him favor in the church. The story of is Valens’ is of his slow descent into pride.
“By virtue of the great hardship that he endured, he attained to the highest measure of ascesis but fell into pride, being so deluded by the demons that he thought angels were conversing with him and ministering to his every need.”