"It is not possible that the Gospels can be either more or fewer in number than they are. There are four zones of the world in which we live, and four principal winds, and the Church is scattered throughout all the world, and her "pillar and ground" (1 Tm 3, 15) is the Gospel and the Spirit of life; therefore it is fitting that she should have four pillars, breathing out immortality on every side, and vivifying men afresh. The Word, the Shaper of all things, who sits upon the cherubim and upholds all things (Ps 79, 2;He 1,3), who was manifested to men, has given us the Gospel under four aspects, but bound together by one Spirit. David says, when entreating his manifestation, "You that sit between the cherubim, shine forth."(Ps 79,2) For the cherubim, too, were four-faced (Ez 1,6), and their faces were images of the dispensation of the Son of God.
For, as Scripture says, "The first living creature was like a lion," (Rev 4,7) symbolizing his effectual working, his leadership, and royal power; the second was like a calf, signifying his sacrificial and priestly order; but "the third had, as it were, the face as of a man,"-an evident description of his coming as a human being; "the fourth was like a flying eagle," pointing out the gift of the Spirit hovering with its wings over the Church. And therefore the Gospels of John, Luke, Matthew, and Mark are in accord with these living things, among which Christ Jesus is seated.
Such was the form of the living creatures, so was also the character of the Word of God himself: the Word of God himself conversed with the patriarchs before Moses in accordance with his divinity and glory; but for those under the law he instituted a priestly and liturgical service. Afterwards, being made man for us, he sent the gift of the Spirit over all the earth, protecting us with his wings (Ps 16,8) These things being so, all who reject the form the Gospel has taken that is, those who say the Gospels should be more or fewer in number are futile, ignorant, and presumptuous."