Disappointment With God, Philip Yancey, Zondervan, p. 74
Once, as an experiment, the great scientist Isaac Newton stared at the image of the sun reflected in a mirror. The brightness burned into his retina, and he suffered temporary blindness. Even after he hid for three days behind closed shutters, still the bright spot would not fade from his vision. "I used all means to divert my imagination from the sun," he writes, "But if I thought upon him I presently saw his picture though I was in the dark." If he had stared a few minutes longer, Newton might have permanently lost all vision. The chemical receptors that govern eyesight cannot withstand the full force of unfiltered sunlight. There is a parable in Isaac Newton's experiment, and it helps illustrate what the Israelites ultimately learned from the wilderness wanderings. They had attempted to live with the Lord of the Universe visibly present in their midst; but, in the end, out of all the thousands who had so gladly fled Egypt, only two survived God's Presence. If you can barely endure candlelight, how can you gaze at the sun?