The old ones tell that dreams hold great power and drift about at night before coming to the sleeping ones.   To keep the dreamer safe, the old ones created a special web, The Dream Catcher.  To hang above their sleeping places.  When dreams traveled the web paths, the bad dreams lost their way and were entangled, disappearing with the first rays of daybreak
The good dreams, knowing the way, passed through the center and were guided gently to the sleeping ones.