The Venerable Bede (672/3-735), in Marc., i, 1: The beginning of this Gospel should be compared with that of Matthew, in which it is said, “The book of the generation of Jesus Christ, the Son of David, the Son of Abraham.” But here He is called “the Son of God.” Now from both we must understand one Lord Jesus Christ, Son of God, and of man. And fitly the first Evangelist names Him “Son of man,” the second, “Son of God,” that from less things our sense may by degrees mount up to greater, and by faith and the sacraments of the human nature assumed, rise to the acknowledgment of His divine eternity.
Theophylact of Ochrid (1055-1107): The Forerunner of Christ, John the Baptist, therefore, is called an angel, on account of his angelic life and lofty reverence. Again, where he says, “Before thy face,” it is as if he said, Thy messenger is near thee: whence is shown the intimate connection of St. John the Baptist with Christ; for it is their greatest friends who walk next to kings. The “way” is the New Covenant, and the “paths” are the Old, because it is a trodden path. For it was necessary to be prepared for the way, that is, for the New Covenant; but it was right that the paths of the Old Covenant should be straightened.
The Venerable Bede (672/3-735): What he cried is revealed, in that which is added, “Prepare the way of the Lord, make his paths straight.” For whosoever preaches a right faith and good works, what else does he but prepare the way for the Lord’s coming to the hearts of His hearers?
St. Jerome: Now by John as by the bridegroom’s friend, the bride is brought to Christ, just as by a servant Rebecca was brought to Isaac (Gen 24:61).
Gregory the Great (540-614), Moralia, xxxi, 25: John pointed out the Lord, of whom he was the forerunner, even by the kind of his food; for in that our Lord took to Himself the sweetness of the barren Gentiles, he ate wild honey.