Commentaria in Isaiam
The third cause was that John might signify the corrupt morals of his age and of the world, and himself in this world not as in a desert among wild beasts and serpents. Whence he says: “Ye brood of vipers, who hath shewed you to flee from the wrath to come?” Matthew 3:7.
So Diogenes the Cynic, carrying a lamp in the market-place at midday, said that he was looking for men; since those whom he saw he judged to be not men, but beasts and cattle.
PREPARE THE WAY OF THE LORD. For “prepare” the Hebrew has panu, that is, clear away every fault of quality, roughness or unseemliness, but let it be clean, comely and beautiful.
Secondly, Vatablus and Forerius say that this verb has contrary meanings: pana in Kal means to turn the face toward, but in Piel it means to turn away from the face, to cleanse. Hence they render it: Cleanse the way of the Lord, that is, from mud and filth. Thirdly, and fittingly for what follows, panu may be rendered make angular, that is, square, level exactly, the way of the Lord; for pinna signifies a corner. Hence, repeating and explaining the same, he adds: “Make straight in the wilderness the paths of our God,” as if to say: Behold, your Christ will soon fill, raise up and level the valleys, that is, the lowly, by greatness of soul and confidence in God; let him who is rough in his ways compose himself to gentleness and modesty. Again, as Tertullian says, book 5 Against Marcion: “Christ will make the hills level with the valleys, and will direct crooked things into straightness and plains, because he will convert all the difficulties of the law into the easiness and equity of the Gospel.” And this is the reason why he used the future, not the optative, saying: “Shall be filled,” not, let it be filled. So Cyril.
For: the Hebrew vau often signifies this; it gives the reason why the way must be prepared.
The Lord is about to come, that he may be inaugurated as king; therefore level the ways for him, that is, remove every hindrance that could offend or dishonour him; take away errors, vices and sins.
AND THE GLORY. That is, the glorious humanity of Christ; and the Godhead hidden in it will be plain to the eyes of all.
It is the same to say “Prepare the way of the Lord” as “Do penance, for the kingdom of heaven is at hand”; for this was the voice and preaching of St. John, as is plain from Matthew 3.
Maldonatus and others, who think that the return from Babylon is treated here, hold that there is an allusion to the departure of the Hebrews from Egypt, for whom a way was opened by God in the Red Sea and in the desert; as if to say: A way will be prepared for the captive people returning from Babylon, no otherwise than when they entered the promised land, God prepared and opened a way through the sea and through the desert.
IN THE WILDERNESS. Forerius refers these words to the preceding; for he himself repeats it here, as if to say: The voice of one crying in the desert and in the wilderness. But this repetition, with so great a transposition of words, is harsh. Secondly, Vatablus says that he calls the wilderness a mind barren and uncultivated by the word of God. This is symbolic and mystical. Thirdly, and most plainly, as if to say: Come out to me into the wilderness; here, therefore, with me exhorting you, amend your ways and prepare the way for Christ. The wilderness itself invites to this, that, withdrawn from the crowd, you may give your time to the word of God and to your salvation. So St. Jerome.
4. EVERY VALLEY SHALL BE EXALTED. This is an enallage of mood; for these future verbs are to be explained by the imperative: “shall be exalted,” that is, let it be exalted; “shall be made low,” that is, let it be made low; “shall be,” that is, let them be. For he explains the manner of making straight, or levelling, the way of the Lord: namely, if the valleys are filled and raised, and the mountains and hills, and the oblique, winding and distorted ways, or roundabout paths, “are made straight, and the rough,” that is, steep, “plain.” Take out of your minds everything that is crooked, distorted, uneven, too high or too low; for example, let him who bears in his heart a mountain of pride bring down this swelling; let him who holds in himself the valley of faint-heartedness and sloth fill it, preaching the kingdom of heaven. For all these things are the glory of the Lord. Of old, the cloud or smoke, from the midst of which fire flashed and the terrible voice of the Lord was heard, was called “the glory of the Lord,” Exodus 19:9 and 16. But now, in the new law, God made man, reconciling the world to the Father, teaching everywhere and working miracles, is called “the glory of the Lord,” revealed to the whole world.
AND ALL FLESH SHALL SEE (that is, shall be able to see and experience) TOGETHER THAT THE MOUTH OF THE LORD HATH SPOKEN. As if to say: Then every man shall see in fact fulfilled what the Lord now promises through me and the other Prophets concerning Christ the Saviour. Hence St. Luke, chapter 3, verse 6, explains it clearly, saying: “All flesh shall see the salvation of God,” that is, the Saviour Christ; as if to say: All shall see that the promises so magnificent concerning Christ, made by the Prophets, were promises of God, and shall understand that it was God who made them, when they behold with their eyes the truth of the promises, namely God himself in the flesh. This salvation, or Saviour, is therefore that glory of God which they assert is to be revealed.
6. THE VOICE OF ONE SAYING (as if to say: I, Isaias, hear a voice speaking to me within and suggesting): CRY. AND I SAID (that is, I answered): WHAT SHALL I CRY (to whom the voice said: Cry)? ALL FLESH IS GRASS. Why is Isaias bidden to cry this? What has it to do with what went before? First, Sanchez and others, who think that here is treated of the return from Babylon, explain it thus: This return of yours may seem impossible to you, O Jews, because of the power of the Chaldeans who hold you and are masters of affairs; yet that power of theirs, though it seems to be at its height, is of flesh, and like a flower in spring, which soon withers under the burning sun, dries up and falls away, and becomes hay, because the spirit, that is, the anger and wrath of the Lord, like a burning wind, has blown upon it and scorched it.
Secondly, Forerius refers this to the cessation of Judaism and of the legal ceremonies, which the Apostle, Hebrews 9:10, calls “justices of the flesh,” because they purified and justified the flesh, not the soul; as if to say: The Jews, as the Apostle says, in the flesh glory, and think that circumcision and their other purifications and carnal ceremonies are solid and will be eternal, and from them they hope for justice and salvation. I will, therefore, O Isaias, that you proclaim to the carnal Jews that all these things, since they are flesh and lack spirit, are like grass or hay, earthly and fleeting, and therefore soon to be dried up and abolished.
Thirdly, and truly, Isaias here prescribes the manner of preparing the way for the Lord, and teaches that it is humility; namely, that men should think and judge themselves to be flesh, and all flesh to be grass, and the glory of flesh to be like the flower of grass. For this humble meditation levels all that is high, crooked and rough in our soul, takes away all vices, plants all virtues, and draws to itself all the grace of God: “For when,” as Sanchez rightly says, “the humble man sees everything in himself, or thinks he sees it, empty and deep, he brings it about that God, who, as in natural things so also in the universe of spiritual things, suffers nothing to be empty, fills what the lowly thought finds empty in itself.” And as, experience teaches daily, there is nothing in the humble man on which men may stumble, strike and take offence, so in the humble there is nothing that deters God from lodging there, whence it comes that God makes in him his house and temple for himself.
Again, Isaias is bidden to cry: “All flesh is grass,” that men may understand how far the Word of God lowered and emptied himself for their sake, and how immense was the divine goodness, by which he willed that his Christ should descend to men so weak and frail as to be like the grass and the flower that at once withers; and that men may at the same time know that they come to this grace and immortal glory of Christ not by the powers of nature, but by the gift of God, if, namely, they be joined with the grass, that is, with the flesh of the Word, which remaineth for ever. So Theodoret, Procopius, St. Jerome and others.
See here, then: the Word, when he was made flesh, was made grass; because all flesh is grass, and therefore, to foreshadow this, he willed to be laid in the manger and the hay, and, as the Church sings:
He shrank not from the manger, he endured to lie on hay.