Why do we draw rays when we can't see them?

 As a child I learned to draw rays from the sun coming from a circle. Here on the lantern in the Wigton stained glass there are rays. But we can't ordinarily see rays so why do we draw them?

Take a look at the second picture here. And I've posted about this camera effect before. I think the answer will be that what we see is affected by diffraction. And here's the reference. It's called diffraction spikes caused by eye lashes or eye lids when squinting.