I closed my eyes again, thinking of the Face. I had to force my mind to turn around in its tracks and look, for it didn't want to confront that infinite complexity again. The Face was painful to see. It was too intricate, too involved with emotions complex beyond our grasp. It was painful for the mind to think of it, straining to understand the inscrutable things that experience had etched upon those mountain-high features.
"Is it a portrait?" I asked suddenly. "Or a composite? What is the Face?"
"A city," De Kalb said. "A nation. The ultimate in human destiny — and a call for help. And much more that we'll never understand."

Ch. 3 : The Vision Of Time - The Time Axis (1949)