“Neither do people put.” This is an expansion of what Jesus taught in Matt. 9:15-16 (see commentary on Matt. 9:16). Old wineskins get stiff and inflexible, and so when the new wine ferments and expands, the old skin cannot expand with it like a new wineskin can, and so it bursts. Occasionally the pressure of fermentation is so great that even sometimes our modern glass bottles burst if wine is incorrectly or prematurely bottled. The understanding and way of doing things that Jesus was bringing to Judaism was “new wine” that could not be put in the “old wineskins” of the religious understanding of the Law and Prophets that was held by the religious leaders of his time. They, and the generations before them, had so thoroughly perverted the true meaning of the Law that they had become “blind guides” (Matt. 15:14). Jesus said that if you put the new wine (the new commandments and the new understanding of the Law that Jesus brought) and put it in the “old wineskins,” they would burst. Indeed, that is exactly what happened. His death and resurrection fulfilled the Law in such a way that the Law, if it was alone and apart from the risen Messiah it pointed to, was considered a veil that blinded the eyes of the heart (2 Cor. 3:15-17).
“wineskin.” A “bottle” or container made from animal skin. [For more on skin-bottles, which were usually made from the skins of goats, see commentary on 1 Sam. 10:3].