1 And in those days cometh John the Baptist preaching in the desert of Judea. 2 And saying: Do penance: for the kingdom of heaven is at hand.
Chrysostom: He preaches what the Jews had never heard, not even from the Prophets, Heaven, namely, and the Kingdom that is there, and of the kingdoms of the earth he says nothing. Thus by the novelty of those things of which he speaks, he gains their attention to Him whom he preaches.
Remigius: “The Kingdom of Heaven” has a fourfold meaning. It is said, of Christ, as “The Kingdom of God is within you.” [Luke 17:21] Of Holy Scripture, as, “The Kingdom of God shall be taken from you, and shall be given to a nation bringing forth the fruits thereof.” [Matt 21:43] Of the Holy Church, as, “The Kingdom of Heaven is like unto ten virgins.” [Matt 25:1] Of the abode above, as, “Many shall come from the East and the West, and shall sit down in the Kingdom of Heaven.” [Matt 8:11] And all these significations may be here understood.
3 For this is he that was spoken of by Isaias the prophet, saying: A voice of one crying in the desert, Prepare ye the way of the Lord, make straight his paths. 4 And the same John had his garment of camels’ hair, and a leathern girdle about his loins: and his meat was locusts and wild honey. 5 Then went out to him Jerusalem and all Judea, and all the country about Jordan: 6 And were baptized by him in the Jordan, confessing their sins.
Pseudo-Chrysostom: The voice is a confused sound, discovering no secret of the heart, only signifying that he who utters it desires to say somewhat; it is the word that is the speech that openeth the mystery of the heart. Voice is common to men and other animals, word peculiar to man. John then is called the voice and not the word, because God did not discover His counsels through him, but only signified that He was about to do something among men; but afterwards by His Son he fully opened the mystery of his will.
Gregory: “Crying in the desert,” because he shews to deserted and forlorn Judaea the approaching consolation of her Redeemer.
Scripture from the Douay-Rheims Bible. Commentary from St. Thomas Aquinas, Catena Aurea, Vol. I (London: Rivington, 1842).