Ezekiel 1:22

"And the likeness over the heads of the living creatures was of a firmament, like the appearance of terrible crystal, stretched above their heads." With the Lord's generosity, we shall explain these things in two ways, so that we may leave it to the reader's judgment to decide what should be chosen. For by the name of firmament, the heavenly powers can be understood. This firmament is rightly said to be like the appearance of crystal, because crystal is indeed exceedingly strong, yet it is solidified from water. And the angelic nature, when it was created, received free will—whether it wished to persist in humility and remain in the sight of almighty God, or whether it would slip into pride and fall from blessedness—it was like water by comparison. But because, while others were falling, the holy angels persisted in their blessedness, and received this as a gift, that they could no longer fall at all, their nature in them, because it can no longer be led about changeably, was hardened as if into the solidity of crystal. This crystal is said to be terrible and stretched out over the heads of the living creatures, because those angelic powers which stand in the presence of almighty God are terrifying and fearful to us who are still placed in this corruption. Their joys, because they exceed the perception of our minds, are said to be above the heads of the living creatures. For who, placed in corruptible flesh, could comprehend what that ineffable and endless joy of the angels might be? What blessedness it is, to see the face of the Creator without failing, and to persist in delight in Him without change? However, by the name of firmament, our Redeemer himself can be understood figuratively—true God above all things, and made perfect man among all things, in whom our nature has been confirmed with the Father. Of whom it is also said prophetically through the Psalmist: "Let your hand be upon the man of your right hand, and upon the son of man whom you have confirmed for yourself." For human nature, before it was taken up by the Creator of all things, was earth; for it was not firmament. Indeed, to sinful man it was said: "You are earth, and to earth you shall go." But after it was assumed by the Author of all things, and raised up into the heavens, and led above the angels, that which was earth became firmament. But what likeness the firmament that is seen has…

(Verse 22 onwards) And the likeness above the heads of the living creatures was like the appearance of a crystal dreadful ice; extended above their heads was what appeared to be a firmament. Under the firmament their wings were straight, one toward another. Each of them had two wings that covered their bodies, and each one had two wings that covered one side. And I heard the sound of the wings, like the sound of many waters, like the sound of the Almighty God. When they walked, it was like the sound of a multitude, like the sound of a camp; and when they stood still, their wings were let down. For when the voice was being made above the firmament that was above their heads, they would stand and submit their wings. And above the firmament that was over their heads, there was a likeness of a throne, and above the likeness of the throne, there was a likeness as the appearance of a man from above. Wherever we would place ourselves, their wings were straight, and like the sound or voice of the exalted God, the seventy translated it. Their wings were extended and flying; and like a strong voice: which in Hebrew is called 'Almighty' (Saddai). Many things in this chapter and in other chapters have been omitted by them, which they have chosen to skip due to their length. But what we have interpreted more clearly, from one to another: each one covered their body with two wings, and the other likewise covered theirs, for which it is written in Hebrew, a man, on account of his sister, covered his body with two wings, and a man likewise covered his; therefore, after woman, man is put in the same person, so that we may not think of gender in heavenly things: since in one and the same way, according to the Hebrew usage, both man and woman are called the same. Moreover, there appears above four living creatures and as many wheels, the likeness of the firmament, which we call the sky, having the appearance of crystal, which is most pure, and is said to solidify from clean and shining waters by excessive coldness - as much as water is also constricted by frost and called κρύσταλλος in Greek. But it was fitting that in the higher things there be extraordinary purity, which protects all things, that is, rational and wise virtues, and the course of the four seasons, and the regions of the world, and the order of all things, and the preaching of the Gospel, which is understood…