My crutch is light rays. I imagine that a light source, a candle for example, emits actual countable rays of light. Not a sea of photons or waves of electromagnetic flux, but thousands of individual rays of light. My rays are straight lines extending in every direction from a light source. They may be refracted through lenses, reflected by surfaces, and often absorbed.
Raw light is measured in lumens .
Think of a lumen as a ray. A light source, like a flame or a filament, produces a certain number of lumens. Imainge the source having some number of rays going out in all directions. A candle has a few rays. A tungsten lamp has many rays.