Paul Evans tells the story of a farmer who established certain guidelines for his teenage son, one of which was that the boy had to be in at a certain hour.  But the lad had a hard time getting home by the deadline.  Finally the father said, "Son, if you aren't home by 12, I'll lock the door and you can't sleep at home."  Sure enough, on Saturday night the hours began to fly quickly as the boy was having fun with his friends.  At 12 the father arose and looked down the road for his son, and with a sigh, he finally turned the lock on the front door and went to bed.  He was still awake when he heard the son come home and try the door.  The son had never seen it locked before, and rattle it as he might, the door wouldn't open.