Updated: May 14, 2020
If you look toward the blazing sun in the sky, you encounter blinding light. Where does this light come from?
Everything we see of the external world enters through our eyes. The retina then relays an electrical signal from our eyes to our brain via the optic nerves. The brain then interprets that signal as the visual world, including the light of the sun.
If the optic nerves are cut, no information can be relayed from the eyes to the brain, and therefore, according to our current scientific theories of perception, we could not see anything of the outside world, including its light. That means the light we see is coming from the brain. If you shut off the brain you don’t see light. If you turn it back on, you see light.
Now consider this. The brain is encased in the skull. It receives no light from the outer world. It only receives electrical signals via the optic nerve in the form of fluctuating ion concentrations. If the brain is literally in the dark, and it receives no light from the outside world, where does the light that the brain interprets come from?
For more, check out this course.