The Greek word a·skosʹ designates a bag or bottle made of a whole animal skin. Jesus Christ said: “Neither do people put new wine into old wineskins [skin bags, Int]; but if they do, then the wineskins burst and the wine spills out and the wineskins are ruined. But people put new wine into new wineskins, and both things are preserved.” (Mt 9:17; Mr 2:22; Lu 5:37, 38) As new wine ferments, it generates carbon dioxide gas that exerts pressure on the skin bottles. New skins expand; old, inflexible ones burst under the pressure.
This illustration was part of Jesus’ answer as to why his disciples did not conform to all the old customs and practices of the Pharisees. Jesus evidently implied that the truth of Christianity was too powerful and energetic to be retained by the old system of Judaism, which lacked vitality and elasticity and which was fast passing away. (Mt 9:14-16) For a general discussion of skin bottles and their uses, see BOTTLE.