Ezekiel 1:16

If you consider the way in which the universe moves in different and contrary ways, whether you think it is in error or whether you think it is of a different nature from us, you see the meaning of "a wheel within a wheel." But as far as all that is concerned, the God of the whole universe directs everything and makes everything to move where he wills, in Christ Jesus, to whom be glory and dominion for ever and ever.

(Verse 15 and following) And as I looked at the animals, a wheel appeared on the earth beside the animals, having four faces. And the appearance of the wheels and their work was like the vision of the sea, and the four of them had the same likeness, and their appearance and work was as a wheel within a wheel. They went in the four directions, and they did not turn as they walked. The wheels also had a height and a terrifying appearance, and the whole body was full of eyes all around the four of them. LXX: And I saw, and behold, a wheel was following animals four over the earth. And the appearance of the wheels and their construction was like the color of tarshish. And their appearance was in four: and their work was as it were a wheel within a wheel. They walked in their four parts, and did not turn back when they walked. And their backs and their height were to them. And I saw them, and their backs were full of eyes all around the four. Up to this point, the picture describes the four living creatures that had four faces, following the spirits and the cloud that was in the midst of the spirit, now the individual wheels are mentioned for each animal, which were not attached to the animals but followed them. Or a wheel appeared upon the Earth, which, divided into four, had as many faces as the number of animals that followed. And such was the similarity of the four wheels to the four following animals, that one wheel was truly believed. And their work and creation was like the vision of tharsis, which we turn into the sea. The eagle placed the hyacinth; which stone resembles the sky. And their appearance was like one wheel in another, so that you would not believe it was one wheel, but rather one wheel joined to another. They were moving in four directions, and they were not being dragged or turned back. […]

Ezechiel beheld within figures resembling four living creatures, and later there appeared a wheel within another. Then the Prophet says that "the appearance of the wheels and the work of them was like the appearance of the sea," and that it was "as it were …

Rightly are the sacred utterances said to be similar to the vision of the sea, because in them there are great volumes of sentences, heaps of meanings. Nor is it undeservedly that Sacred Scripture is said to be similar to the sea, because the sentences of speech are confirmed in it through the sacrament of baptism. Or certainly it must be considered that we sail by ships into the sea when we proceed toward desired lands. But what is in our desire except that land about which it is written: "My portion is in the land of the living"? But he who crosses the sea is carried, as I said, by wood. And we know that Sacred Scripture announces to us the wood of the cross through the law, when it says: "Cursed is everyone who hangs on a tree." Paul attests this concerning our Redeemer, saying: "Made a curse for us." Through the prophets also it announces the wood, when it is said: "The Lord will reign from the wood." And again: "Let us put wood in his bread." But through the Gospel the wood of the cross is openly shown, where the very passion of the Lord which was prophesied is declared. Through the apostles, moreover, this same cross is also held in words and works, when Paul says: "The world is crucified to me, and I to the world." And again: "But far be it from me to glory except in the cross of our Lord Jesus Christ." Therefore for us who proceed toward the eternal homeland, Sacred Scripture through its four faces is a sea. It announces the cross, because it carries us to the land of the living by wood. […]

There is a wondrous conformity between the Old and New Testaments, not only in the content of their meanings, but also in the fourfold structure of their parts. As a figure and sign of this, Ezekiel saw wheels with four faces and a wheel within …