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 (c. 460-c. 377 B.C.), The Sacred Disease