"How you have fallen from heaven, O daystar, rising in the morning! You are shattered on the earth, you who sent to all the nations. But you said in your mind: I will ascend into heaven. I will set my throne above the stars of heaven. I will sit on a high mountain, on the high mountains toward the north. I will ascend above the clouds. I will be like the Most High. But now you shall descend into Hades, to the foundations of the earth" (Is 14:12-14).
According to the text cited by Saint Cassian, the prophet's words may be explained in this way.
How have you fallen from heaven, O Light-bearer, Lucifer, who rose in the morning? You have crashed to the earth, you who wounded the nations and said in your heart: I will ascend into heaven. I will raise my throne above the stars of God. I will sit on the mountain of the covenant, on the wings of Aquilo, the north wind. I will ascend above the breadth of the clouds and will be like the Most High.
The lament commanded by God to the Prophet Ezekiel over the prince of Tyre is applied by Saints Andrew of Caesarea and Cassian to the chief fallen angel.
In our Bible he is likened to a cherub. In the text cited by Saint Cassian he is directly called a cherub. The very meaning of the text compels us to refer the prophet's inspired lament to him.
"The word of the Lord came to me," says the Prophet, "saying: Son of man, take up a lamentation over the prince of Tyre, and say to him: Thus says Adonai the Lord: You are the seal of likeness, full of wisdom and a crown of beauty. You were in the delight of the paradise of God. You were adorned with every precious stone. With gold you filled your treasuries and your storehouses from the day you were created. I placed you with the cherub on the holy mountain of God. You were in the midst of the fiery stones. You were blameless in your days from the day you were created, until unrighteousness was found in you. By the multitude of your trade you filled your treasuries with lawlessness, and you sinned. You were wounded from the mountain of God, and the overshadowing cherub brought you down from the midst of the fiery stones. Your heart was lifted up because of your beauty. Your skill was corrupted along with your beauty. Because of the multitude of your sins, I cast you to the earth. I gave you as a spectacle before kings. Because of the multitude of your sins and the unrighteousness of your trade, you defiled your sanctuaries" (Ezek 28:11-18).
These words of the Prophet can in no way be referred to an earthly prince of Tyre. Tyre was founded by idolaters and constantly remained in impiety.
Therefore its prince could never have been the seal of likeness and the crown of righteousness. He could never have been placed in paradise and numbered among the cherubim.
There is nothing strange in the Lord commanding the Prophet to lament a fallen angel. In commanding this lament, the all-good Lord reveals to us His great mercy and compassion for His perished creature.
When a man feels in his soul, by the gift of the Holy Spirit, an abundance of supernatural grace-filled mercy, he cannot but have compassion for all creation subjected to the fall and tormented in it.
He does not exclude even the hardened enemies of the human race, the demons.
Saint Cassian reads verses 14, 15, and 16 in this way: You are the cherub, stretched out and covering, and I placed you on the holy mountain of God. You walked in the midst of fiery stones, perfect in your ways from the day of your creation, until unrighteousness was found in you. In the multitude of your trade your inward parts were filled with unrighteousness, and you sinned. I cast you down from the mountain of God, and I destroyed you, O covering cherub, from the midst of the fiery stones. Under the name of fiery stones, Saint Andrew of Caesarea understands the other heavenly angelic powers.