It is extremely difficult at the present time to say whether insanity is increasing.  Statistics in all lands giving the numbers committed to insane hospitals show on their face a great increase, but so many factors enter into these statistics that their value is uncertain.  There is now an ever-increasing provision for the care of the insane.  Owing to the recognition of insanity as a part of nervous disease and its separation from criminality there is no longer the same attempt to conceal it as was formerly the case, and hospitals for the insane are no longer associated with ideas of Bedlam.  It is generally believed that modern conditions in the hurry and excitement of life, and the extreme social differences, the greater urban life, the greater extension of factory life, all tend to an increase in insanity, but there is no absolute proof that this is true.  We know very little about insanity in the Middle Ages, but the conditions then were not conducive to a quiet life.  There prevailed then as now excess and want, luxury and poverty, enjoyment and deprivations, balls and dinner parties and other features of the social game.  There were factions in the cities, public executions, not infrequent sieges, scenes of horror, epidemics, famines, and all these combined with religious superstition and the often unjust and cruel laws should have been factors for insanity.  There were actual epidemics of insanity affecting masses of the population, as shown in the children’s crusade, the Jewish massacres and the dancing mania in the Rhine provinces.  Where civilization seems to be the highest, statistics show the most insane, but this most probably depends upon better recognition of the condition and better provision for asylum care.

The so-called functional diseases have a close relation with diseases of the nervous system, for they chiefly concern the reactions of nerve tissue.  Disease expressing itself in disturbance of function only, does not seem to fit in with the conceptions of disease which have been expressed, nor can we imagine a disturbance of function which does not depend upon a change of material.  Living matter does not differ intrinsically from any other sort of matter; like other matter its reactions depend upon its composition structure[1] and the character of the action exerted upon it.  By functional disease there is expressed merely that no anatomical or chemical change is discoverable in the material which gives the unusual reaction.  The further our researches into the nature of disease extend, particularly the researches into the physiology and chemistry of disease, the smaller is the area of functional disease.  In functional disease there may be either vague discomfort or actual pain under conditions when usually such would not be experienced, and on examination no condition is found which in the vast majority of cases would alone give rise to that impression on the nervous system which is interpreted as pain.  In the production of the sensations