Meditation in a Toolshed

I found this essay by C.S. Lewis - and the analogy especially - insightful. It's called Meditation in a Toolshed.

I was standing today in the dark toolshed. The
sun was shining outside and through the crack at
the top of the door there came a sunbeam. From
where I stood that beam of light, with the specks
of dust floating in it, was the most striking thing in
the place. Everything else was almost pitch-black.
I was seeing the beam, not seeing things by it.
Then I moved, so that the beam fell on my
eyes. Instantly the whole previous picture
vanished. I saw no toolshed, and (above all) no
beam. Instead I saw, framed in the irregular cranny
at the top of the door, green leaves moving on the
branches of a tree outside and beyond that, 90 odd
million miles away, the sun. Looking along the
beam, and looking at the beam are very different
experiences.