BRAIN, n.
An apparatus with which we think what we think. That which distinguishes the man who is content to _be_ something from the man who wishes to _do_ something. A man of great wealth, or one who has been pitchforked into high station, has commonly such a headful of brain that his neighbors cannot keep their hats on. In our civilization, and under our republican form of government, brain is so highly honored that it is rewarded by exemption from the cares of office.
--Ambrose Bierce - The Devil's Dictionary