Neither do men put new wine into old wineskins: else the wineskins break, and the wine runs out, and the wineskins perish: but they put new wine into new wineskins, and both are preserved.
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Theophylact of Ochrid
The disciples, He says, have not yet become strong, and therefore require forbearance. The heavy burden of commandments ought not to be laid upon them. Jesus also said these things to teach the disciples that later, when they would go out into all the world to make disciples, they too should use forbearance. The "piece of unshrunk cloth" means fasting, as does the "new wine." The "old garment" and the "old wineskins" mean the weakness of the disciples.