Let there be light

I have this prism made of a large circle of glass with small round raised circles on the surface that sits on a table near my bedroom  window. A sliver of morning light came all the way through the house from the front window - through the dining room, the kitchen, the doorway of the bedroom and stuck the prism at just the right angle to throw a shadow of it on the blind behind it. This can only happen a couple of times a year when the sun is at the right position in the sky. I think it is so cool.