What was that?

Today I was thinking about how it is that the light around us - the illumination that appears as an obvious natural state of clarity - is moving - like the wind, but when the wind stops, there is still air.  When the source of light stops emitting, the light keeps going, away, and is gone from where it once was.  Our light, constantly, quickly speeding past me, not so infinite, not so absolute, not so eternal, gone.  Darkness on the other hand...