What else than a natural and mighty palimpsest is the human brain?

Such a palimpsest is my brain; such a palimpsest, O reader! is yours. Everlasting layers of ideas, images, feelings, have fallen upon your brain softly as light. Each succession has seemed to bury all that went before. And yet in reality not one has been extinguished. The fleeting accidents of a man's life, and its external shows, may indeed be irrelate and incongruous; but the organizing principles which fuse into harmony, and gather about fixed predetermined centres, whatever heterogeneous elements life may have accumulated from without, will not permit the grandeur of human unity greatly to be violated, or its ultimate repose to be troubled in the retrospect from dying moments, or from other great convulsions.