Men ought to know that from the brain and from the brain only arise our
pleasures, joys, laughter, and jests as well as our sorrows, pains, griefs
and tears. ... It is the same thing which makes us mad or delirious,
inspires us with dread and fear, whether by night or by day, brings us
sleeplessness, inopportune mistakes, aimless anxieties, absent-mindedness
and acts that are contrary to habit...
- -- Hippocrates "The Sacred Disease"