What does Jesus mean by the patch and the wineskins (9:16-17)?

Matthew gives Jesus's words without an explanation, and these notes don't add one. John's disciples had asked, "Why do we and the Pharisees fast often, but your disciples don’t fast?" (9:14). Jesus answered with the bridegroom (9:15), and then with two pictures. "No one puts a piece of unshrunk cloth on an old garment; for the patch would tear away from the garment, and a worse hole is made" (9:16). "Neither do people put new wine into old wineskins, or else the skins would burst, and the wine be spilled, and the skins ruined. No, they put new wine into fresh wineskins, and both are preserved." (9:17). Matthew says no more about them, and doesn't say what John's disciples made of the answer. Mark gives the two pictures in his own words (Mark 2:21-22). Luke says, "He also told a parable to them" (Luke 5:36), and gives them in his own words (Luke 5:36-38). These notes set them side by side and don't say what the old garment, the new wine or the wineskins stand for.