2. We have so far been mainly considering the relations to the production of neuralgia of certain conditions of the central nervous system which indisputably are inherent from birth. Let us now pass quite to the other extreme, and consider a class of momenta which take a decided part in producing many neuralgiæ, but which are altogether accidental and factitious, and cannot be included among the necessary hostile conditions of life. To push the contrast to the utmost, let us inquire first, what amount of influence in the production of neuralgia can be given by such a purely "functional" influence as educational misdirection of intellect and emotion?
It is somewhat strange, though every one accepts as a mere truism the maxim that sudden emotional shock may produce almost any degree or variety of nervous disorder, the slower but far surer influence of long-continued mental habit is often practically ignored. It cannot, indeed, be left out of sight as a cause of disorders of the mind itself, nor are there many who would deny that such diseases as cerebral softening are, in a considerable number of cases, the premature ending to a life that has been broken down by harassing work and anxiety. But what is far less appreciated is the tendency of certain unfortunate mental surroundings and modes of mental life to produce a generally neurotic condition, which may express itself in a variety of functional disorders, among which not the least common is neuralgia.