Accustomed to Judaism and Christianity being two distinct religions, it's difficult for us to appreciate the attempts our earliest Christian authors made to clarify the unique approach to Judaism which the historical Jesus offered his followers.
Originally Christianity wasn't looked upon as separate from Judaism. If Paul of Tarsus, for instance, were asked to state his religion a few minutes before his early 60s martyrdom, no doubt he would have responded, "Jew!" Throughout his ministry, he never seems to have thought of himself as practicing a new religion. He simply bought into the reform of Judaism which the resurrected carpenter from Nazareth had proclaimed.
When pressed by his fellow Jews to define the difference Jesus had brought to his practice of Judaism, Paul would probably respond as he does in today's II Corinthians passage. Going back to Ezekiel's dream of a new covenant, he reminds his readers, "You are a letter of Christ . . . written not with ink but by the Spirit of the living God, not on tablets of stone but on tablets that are hearts of flesh. . . . God has qualified us as ministers of a new covenant, not of the letter, but of spirit, for the letter brings death, but the Spirit gives life." Jesus of Nazareth had simply demanded that his followers be true Sprit-filled Jews.
As a prophetic reformer, Jesus understood that humans are always prone to fall into the trap of believing that written and rules and regulations are at the heart of faith. Throughout his earthly ministry he asked people to return to the frame of mind which existed in Judaism before the written law came into a being: to develop a way of looking at Yahweh working in their lives that went deeper than any law could penetrate.
Hosea called his 8th century BCE people to do the same: to return mentally and emotionally to that period when Yahweh spoke to people's hearts; to go back to the Exodus when Yahweh wasn't a great law-giver, but a husband espoused to Israel "in right and in justice, in love and in mercy." It was a time when the Chosen People worked at "knowing Yahweh." (If the Hebrew word for "know" is applied to humans, it usually connotes an "intimate" relationship.)
His quest for people to change the way they perceive God seems to be why the historical Jesus so often used parables. Teachers only employ parables when they're not just interested in helping people acquire new knowledge, but are attempting to help them create new ways of processing the knowledge they already have. Jesus' goal is to instill a new mentality in his followers; a new way of understanding their relationship with Yahweh. This is clear from the two mini-parables he uses in today's gospel pericope.
When someone criticizes his disciples for not fasting, Jesus not only gives an immediate defense of their behavior, but also explains that their refusal to fast demonstrates that they're approaching their faith with a frame of mind shared by few of their contemporaries. He talks about the folly of sewing an unshrunken patch on a shrunken cloak, or pouring new wine into old wineskins. In each case, the new destroys the old. His point: to appreciate his actions and teaching, one must start from scratch, acquiring a new way of looking at God and our relationship with God. If someone has a law-oriented relationship, then refusing to fast can be a destructive element in the community. On the other hand, if someone approaches God from a position of mutual love, then fasting or not fasting is insignificant.
Christians today still need parables. Though we learned in great detail the "practice" and laws of our religion, some of us are still ignorant about the proper frame of mind and emotion to approach our faith. It's not what we learn that's important. It's how we learn and interpret that makes our faith unique.