Cyril of Jerusalem

After this description of the prophet, we still cannot comprehend as we read. But if we cannot comprehend the throne that he has described, how will we be able to comprehend him who sits on it, the invisible and ineffable God? It is impossible to examine closely the nature of God, but for his works, which we see, we can offer him praise and glory.

Catechetical Lecture 9:3 ↗

Jerome

And in the midst of it is the likeness of four living creatures, and this is their appearance: the likeness of a human in them. And what follows, And there is a brightness in it, should be noted with a mark. Unless the Scripture had added, saying: That is, from the midst of the fire, because of the ambiguity of the word, we might have erred and thought that the appearance or vision was of lightning in the midst of the wind or of a spirit. …

Commentary on Ezekiel ↗

Gregory the Dialogist

"And this was their appearance: there was the likeness of a man in them." Since a little later these holy living creatures are described as distinct in their individual forms, so that one is said to be like a man, another like a lion, another like a calf, and another like an eagle, what does it mean that in this place it is said of all of them together, "The likeness of a man was in them"? …

Homilies on Ezekiel, Book 1, Homily 2 ↗

Bonaventure

Ezechiel beheld "within figures resembling four living creatures;" and the first had the face of a man, the second that of a lion, the third that of an ox, and the fourth that of an eagle. And each one had four faces. All agree that the "four living creatures" represent the writers of Sacred Scriptures, mostly the Prophets and the Evangelists. Ezechiel intends to describe these meanings in the order of their importance: therefore he begins with the natural face of a man, which signifies the literal interpretation. …

Collations on the Hexaemeron, Collation 13 ↗