21 Feb Koan 7
What do we see everywhere but rarely notice?
Light.
Things we see are not things, just light reflecting off things.
Moreover, the essence of things is light; for all things are energy slowed down by the speed of light squared. That is, E=M*C*C is M=E/C*C; Mass is Energy divided by the speed of light squared.
As all things are light, perceiving things as otherwise is an illusion.