A sufficiently complete explanation of my theory as to the pathology and etiology of neuralgia has now been given, although the subject might be elaborated at far greater length; and I hope it will be apparent to the reader that the view now advocated is at once important, and also vouched for by strong evidence. I claim for it that the whole argument shall be taken together, for it is a case of cumulative proof; every link must be weighed and tested, before the remarkable strength of the chain can be felt. And it may fairly be said that, if the proof of a definite kind of material change in a definite organ, as the essential factor in neuralgia, has been established upon reasonable grounds, an important step has been taken toward removing a serious opprobrium and difficulty in practical medicine. Although the true neuralgias are not among the most frequent of human diseases, they form a class of enormous practical importance, for they are sufficiently common to be sure to occur in considerable numbers in the practice of every medical man, and, both from the suffering which they inflict, and the rebelliousness which they often show to treatment, they are among the gravest sources of anxiety which the practitioner is likely to encounter. There are probably few disorders which so often occasion mortification and loss of professional credit to the physician. The helplessness which men, who do not enjoy special opportunities of seeing those diseases with frequency, so often show in dealing with them, is largely caused by the extreme timidity and vagueness with which the standard treatises on medicine deal with the question of their pathology; and a very unfair advantage has thus been given to the specialists, who, by the mere force of opportunity, and continual blind "pegging away" in an entirely empiric manner, have acquired a certain rude skill in the treatment of these maladies which enables them to outshine practitioners who often have far more in them of the veritable _homme instruit_ as regards general scientific education and habits of mind. It will be evident, as a mere abstract proposition, that the enunciation of a reasonable pathology of the disease, and the sweeping away of a mass of unmeaning phrases about "mysterious functional affections" and the like, must be a distinct gain to practitioners of plain common-sense and good general knowledge, to whom neuralgia is merely one of a vast number of different diseases among which their attention and study are divided. And I hope that, in the further remarks on Diagnosis, Prognosis, and Treatment, yet to be made, the value of clear pathological ideas of disease will be brought more practically and clearly into view. [The reader will find, at the end of Part I. of this volume, a note which contains a brief discussion on the "Erschopfung" theory of Jaccoud, and the doctrines of Dr. Handfield Jones respecting inhibition, with which I thought it best not to encumber the text of the present chapter.]