Bede the Venerable — as excerpted in the Catena Aurea on Mark 2:18-22

“(ubi sup.) But in a mystical sense, it may thus be expressed; that the disciples of John and the Pharisees fast, because every man who boasts of the works of the law without faith, who follows the traditions of men, and receives the preaching of Christ with his bodily ear, and not by the faith of the heart, keeps aloof from spiritual goods, and wastes away with a fasting soul. But he who is incorporated into the members of Christ by a faithful love cannot fast, because he feasts upon His Body and Blood. It goes on, No one seweth a piece of rough, that is, new, cloth on an old garment: else the new piece that filleth it up taketh away from the old, and the rent is made worse.”