Matthew 9:17

Old bottles] The most usual Eastern bottles are simply goat-skins drawn off the animal entire. The neck of the animal forms the neck of the bottle. Those used for wine are tanned with oak-bark and seasoned in smoke, which gives a flavour to the wine that is much appreciated. New wine is liable to a certain amount of after-fermentation, so that it cannot safely be stored in old bottles. Our Lord's saying about the old and the new bottles applies properly to the Baptist's teaching, but it may also be applied to Judaism in general. So taken, it means that the forms of Judaism are inadequate to express the spirit of Christianity, and that those who, like the Judaising Christians in the Acts, try to combine the Law with the Gospel and to enforce the Mosaic ritual, are trying to put new wine into old bottles.