In CS Lewis’ Miracles, he wrote about “the frontier between Nature and Supernature” (63). And he said that the “twists and turns” that arise on that frontier are similar to the twists and turns we find on the boundary line of a map. The two regions have separate identities, and yet distinguishing between whether this dent is a part of one region or that bulge a part of another isn’t as obvious as we might think (Turning Aside to See 130).
Viewed in this way, Lewis’ “Nature” denotes the brain and our physical identity. And his “Supernature” denotes consciousness or our spiritual individuality. The boundary line is all but impossible for human beings to distinguish without the light of Christ in our heart and at our side. That’s why God sent His Son.