It seems there are two main lines of thought about what this means. Some say it was something more incidental: when wineskins weren't used they were stored up high at a place where the smoke of the fire (for cooking etc) ended up wasting them away. Another line of thought is that this was a very intentional process, and that new wineskins especially were intentionally placed in the smoke in order to dry them and toughen them for maximum effectiveness/use. The second seems more in line with God's intentions in our afflictions. Scripture affirms affliction only comes "when necessary" and that God is sending it in our lives in a very intentional way for very good reasons/purposes. So I'd like to believe the second is more accurate, but commentators/scholars seem divided. Any thoughts?