As for rainbows, there is a kind of iridescent heaven, in which the whole atmosphere seems to be made of tiny rainbows, one after another. The people who live there belong to the region of the inner eye and are stationed off to the right, out in front and a little bit up above. The entire atmosphere there—all the air—consists of these gleams of light and therefore radiates out of each individual “beacon,” so to speak. A much larger rainbow (compounded of similar smaller ones that are exquisite miniatures of the big one) forms a gorgeous belt around the outside.
Each color, then, consists of many, many rays, so that millions of rays make up a single, all-inclusive rainbow visible to the eye. The rainbow is a modification of the points of light, a modification produced by the heavenly and spiritual forces that create the rainbow and in the process present before the observer’s eyes a picture full of representative meaning.
There is no limit to the different types and varieties of rainbows, several of which I was privileged to see. To grasp in some measure the kind of variation they display, and to see how very many rays of light go into a single visible one, let me describe just one or two.
from Secrets of Heaven, Volume 2, Section 1623