We pursue some thoughts triggered by Psalm 36:9: ‘In your light do we see light.’ And these thoughts are provoked further by the catalyst of a famous quote from C. S. Lewis: ‘I believe in Christianity as I believe that the Sun has risen, not only because I see it, but because by it I see everything else.’
Ordinarily when we seek to have a well-grounded conviction about some claim to truth in this world, we bring all our experience to bear on the claim and try to make sense out of it. What we know from experience before we hear the claim, we apply to the claim to see if it measures up. Does it cohere with what we know to be true? Does it make sense in the light of what we already know? What we know from experience is the standard, the arbiter, the measure of truth.
But what happens when we encounter a claim that says, “I am the Standard, the Arbiter, the Truth”? This claim is unique. It is not like other claims to truth in this world. When the ultimate Measure of all reality speaks, you don’t subject this Measure to the measure of your mind or your experience of the world. He created all that. When the ultimate Standard of all truth and beauty appears, he is not put in the dock to be judged by the prior perceptions of truth and beauty that we bring to the courtroom.
The eternal, absolute original is seen as true and beautiful not because he coheres with what we know but because all the truth and beauty we know coheres in him. It is measured by him, and it is seen flowing from him. He does not make sense, and thus have plausibility, in the light of this world. He brings sense to the world. He is sense. The light that we have in the world does not shine on him and reveal his truth. He is the light of the world, and in his light we see light.
—John Piper, A Peculiar Glory, 158-159