"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..."