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 to remember.  Then the patient is almost sure to fancy himself going insane.  But insanity is a physical disease, implying changes or toxins in the brain cells.  Functional disorders tell another story.  Their cause is different, even though the picture they present is often a close copy of an organic disease.

=Distorted Pictures.= It should not be thought, however, that the symptoms of functional and organic troubles are identical.  Hysteria and neurasthenia closely simulate every imaginable physical disease, but they do not exactly parallel any one of them.  It may take a skilled eye to discover the differences, but differences there are.  Functional troubles usually show a near-picture of organic disease, with just enough contradictory or inconsistent features to furnish a clue as to their real nature.  For this reason it is important that the treatment of the disease be solely the province of the physician; for only the carefully trained in all the requirements of diagnosis can differentiate the pseudo from the real, the innocuous from the disastrous.

False or nervous neuritis may feel like real neuritis (the result of poisons in the blood), but it gives itself away when it localizes itself in parts of the body where there is no nerve trunk.  The exhaustion of neurasthenia sometimes seems extreme enough to be the result of a dangerous physical condition; but when this exhaustion disappears as if by magic under the proper kind of treatment, we know that the trouble cannot be in the body.  Let it be said, then, with all the emphasis we can command, “nerves” are not physical.  Laboratory investigation, contradictory symptoms, and response to treatment all bear witness to this fact.  Whatever symptoms of disturbance there may be in pure nervousness, the nerves and organs can in no way be shown to be diseased.