The crystal sphere of thought is as concentrical as the geological structure of the globe. As our soils and rocks lie in strata, concentric strata, so do all men's thinkings run laterally, never vertically.
Ralph Waldo Emerson (1803–1882), U.S. essayist, poet, philosopher. Speech, August 11, 1841, at Waterville College, Maine before the Society of the Adelphi. "The Method of Nature," Nature, Addresses, and Lectures (1849).