Subject: Dappled Light

Morning sunlight filtering through trees throws circles of light on 
the wall.  Where the circles overlap, the ellipse created is twice 
and three times as bright depending on the number of overlapping 
circles.  1. Why circles of light and not irregular shapes
          2. Is this concentration of light finite? and at what point?
          3. Is there something useful here?

Re: Dappled Light