A defense that the Canon need include 4 Gospels, no more, no less

St. Irenaeus (a Doctor of the Church, 2nd Century) Adversus

Haereses III.#11, parts  8-9

It is not possible that the Gospels can be

either more or fewer than they are.  For,

since there are four zones of the world

in which we live, and four principal winds. . .

it is fitting that [the Church] should have

four pillars. . .From which fact, it is evident

that the Word [Greek logos ; Latin verbum]

. . .has given us the Gospel under four

aspects, but bound together by one Spirit. . .

For the cherubim, too, were four-faced . . .

These things being so, all who destroy the

form of the Gospel are vain, unlearned, and

also audacious;  those who represent the

aspects of the Gospel as being either more

in number than as aforesaid, or, on the

other hand, fewer. . .