An angel sits as though at the head when it is proclaimed through the Apostle John: "In the beginning was the Word, and the Word was with God, and the Word was God" (Jn 1:1).
An angel sits as though at the feet when the same Apostle says: "And the Word became flesh, and dwelt among us" (Jn 1:14).
Again, through the two angels we may understand the two Testaments, one given before and the other after. These angels are joined to one another precisely by the place of the Lord's body.
Both Testaments proclaim with one meaning the incarnate, dead, and risen Lord. But the first Testament sits as though at the head, and the latter Testament as though at the feet.
Therefore the two cherubim covering the mercy seat are turned face to face, with their faces toward the mercy seat (Ex 25:20). Cherubim is called fullness of knowledge.
What is signified by the two cherubim, if not the two Testaments? And what is prefigured by the mercy seat, if not the incarnate Lord?
Of Him John says: "He is the propitiation for our sins" (1 Jn 2:2). The Old Testament proclaims what was to be done. The New Testament preaches that it has already been accomplished by the Lord.
Then both cherubim, as it were, look at one another while turning their faces toward the mercy seat. For, seeing the Lord placed between them, they do not disagree in their view.
They proclaim in harmony the mystery of His divine economy.