so it happens that often there is a combination of organic and
functional disease that is puzzling even to a skilled diagnostician.
The first essential is a diagnosis as to whether it be an organic
disease, with accompanying nervous symptoms, or a functional
disturbance complicated by some minor organic trouble. If the main
cause is organic, only physical means can cure it, but if the trouble
is functional, no amount of medicine or surgery, diet or rest, will
touch it; yet the symptoms are so similar and the dividing line is so
elusive, that great skill is sometimes required to determine whether a
given symptom points to a disturbance of physical tissue or only to
behavior.

If the physician is sometimes fooled, how much more the sufferer
himself! Nausea from a healthy stomach is just as sickening as nausea
from a diseased one. A fainting-spell is equally uncomfortable,
whether it come from an impaired heart or simply from one that is
behaving badly for the moment. It must be remembered that in
functional nervousness the trouble is very real. The organs are really
"acting up." Sometimes it is the brain that misbehaves instead of the
stomach or heart. In that case it often reports all kinds of pains
that have no origin outside of the brain. Pain, of course, is
perceived only by the brain. Cut the telegraph wire, the nerve, and no
amount of injury to the finger can cause pain. It is equally true that
a misbehaving brain can report sensations that have no external
cause, that have not come in through the regular channel along the
nerve. The pain feels just the same, is every bit as uncomfortable as
though its cause were external.

Sometimes, instead of reporting false pains, the brain misbehaves in
other ways. It seems to lose its power to decide, to concentrate, or