There was a monk at Beroea who was only slightly educated. One day a book on divination came into his hands, and out of curiosity he read a little bit of it, thereby invoking the demons. As he slept that night, he saw in a dream a giant creature, blacker than any Ethiopian, who said to him:
“Because you have called upon me, I have come. If you will make obeisance to me, I will do what you ask!”
Now the monk recognized that this was the devil, and said to him:
“I worship the Lord God, and Him alone do I serve!”
Then the demon in anger smote him across the face, and said:
“Since you will not fall down and worship me, why did you summon me?”
Then, on account of the pain in his face, the monk awakened, shouting loudly and crying out loud. Others gathered and saw his jaw and cheek very swollen and bruised. It was a very strange sight to behold.
In a few days, the body tissues swelled further and blackened even more, to such a degree that his eyes could not be seen at all. Therefore they sent a message to Saint Dionysios at Mount Olympus to come and investigate the matter.
When Saint Dionysios saw him, he prayed to the Lord and chanted the Supplicatory Canon to the Theotokos. Then he anointed the monk with holy oil, whereupon the afflicted monk recovered and glorified the Lord.
From New Paradise by Monk Agapios of Crete.