A map of the US with only the state boundaries shown appears fairly blank, but zooming in to a region of a large city shows a complicated collection of buildings delineated by streets. The brain turns out to be similar—deceptively simple until you look closely.
 
Given its extraordinary properties, brain tissue is surprisingly unprepossessing. The human cerebral cortex appears to be made of a whitish substance about as featureless as blancmange. Its monotony is broken only by the folding of the cortical surface that enables more brain tissue to pack in the skull. The same featurelessness holds true for a small sample of brain tissue when removed and viewed under a light microscope. But if appropriate dyes are applied, vast numbers of distinct cells appear.
 

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