Dr. J. C. Prichard, in writing of diseases of the nervous system, has well said that “few diseases are better characterized by them symptoms than epilepsy; yet in this instance there is such a variety in the phenomena as renders it difficult to contrive a definition in a few words which may comprehend every form of the complaint.” I have said that when convulsions become chronic they are considered to take on an epileptiform character. Now, although we know that in a few cases involuntary spasm may take place in sleep, _i.e._ with loss of consciousness, I think we may, for all general purposes, take as a definition of epilepsy a chronic convulsive disease, each convulsive attack being accompanied with “sudden and complete loss of consciousness,” this latter symptom being considered by the late Dr. Todd[5] as “the pathognomonic symptom of the disease,” but only, as Dr. Reynolds[6] has shown, “when it occurs as a paroxysmal or occasional event.” Footnote 5: _Medical Times and Gazette_, August 5, 1854, p. 129. Footnote 6: _Op. cit._, p. 31. The causes of epilepsy are various—“partly physical, partly immaterial.” Of the former are injuries and tumours of the brain or meninges, intestinal worms, renal and biliary calculi, &c. &c. These are termed by Dr. Handfield Jones[7] “eccentric causes.” As “centric causes,” he names “poisoning of the blood from retention of excrementitious matter; this, by deranging the nutrition of the nervous tissue, generates the abnormal excitability, which then manifests itself without any special irritant. Various causes of exhaustion, such as hæmorrhage and excessive discharges, venereal excesses, prolonged want of sleep, unremitting pain,” &c., are all “centric” causes of epilepsy. Footnote 7: _Op. cit._, p. 209. Dr. Reynolds is right in considering epilepsy an idiopathic disease, inasmuch as it occurs, without discoverable organic lesion with which it can be associated, and because there is no structural lesion of the brain, or spinal cord, to be found constantly associated with it; but when he says that it is idiopathic because, “in many cases, eccentric irritation cannot be shown to be the cause of the attacks,” I cannot go with him. Epilepsy is a name signifying a disease, which may be idiopathic, or may arise from a variety of causes; but that eccentric irritation is a powerful and very frequent cause, there is not the slightest doubt. Dr. Reynolds classes it as second of six in a table given in his book, physical conditions being mentioned as first; and finding, in a hundred cases, that 24·63 have no assignable cause, and 18·84 are doubtful, he gives 13·04 as due to eccentric irritation.