Bede the Venerable — as excerpted in the Catena Aurea on John 3:27-30

“Who art thou then, since thou art not the Christ, and who is He to Whom thou bearest witness? John replies, He is the Bridegroom; I am the friend of the Bridegroom, sent to prepare the Bride for His approach: He that hath the Bride, is the Bridegroom. By the Bride he means the Church, gathered from amongst all nations; a Virgin in purity of heart, in perfection of love, in the bond of peace, in chastity of mind and body; in the unity of the Catholic faith; for in vain is she a virgin in body, who continueth not a virgin in mind. This Bride hath Christ joined unto Himself in marriage, and redeemed with the price of His own Blood.”