It is not an easy matter, at least I have not found it so in my experience, when brought face to face with an actual case of in sanity, and asked to state the cause of it, to do so definitely and satisfactorily. The uncertainty springs from the fact that, in the great majority of cases, there has been a concurrence of co-operating conditions, not one single effective cause. Two persons are exposed to a similar heavy mental shock: one of them is driven mad by it, but the other is not. Can we say then that the madness has been produced by a moral cause? Not accurately so; for in the former case there has been some innate vice of nervous constitution, some predisposition of it to disease, whereby insanity has been produced by a cause which has had no such ill effect in the latter case. The entire causes have not, then, been in reality the same. And what we have to bear in mind is, that all the conditions which conspire to the production of an effect, whether visibly active or seemingly passive, are alike causes, alike agents, and that therefore all the conditions, whether they are in the patient himself or in the circum stances of life in which he is placed, which in a given case co-operate in the production of insanity, must properly be viewed as its causes. Mental derangement sometimes appears as the natural issue of all the precedent conditions of life, mental and bodily, the outcome of the individual character as affected by certain circumstances; the germs of the disease have been latent in the foundations of the character, and the final outbreak is but the explosion of a long train of antecedent preparations. In vain, then, is it in many cases to attempt to fix accurately on a single cause, moral or physical; a common mistake on the part of those, who think to do so being to fix upon what is really an early symptom of the disease as the supposed cause of it. Religion, self-abuse, intemperance, have all at times been put down as the causes of mental derangement, when they were really morbid symptoms.

To the students of mind in its healthy as well as in its diseased condition, the doctrine that certain portions of the brain are associated with particular mental powers is necessarily one of engrossing interest. Until lately, however, the facts advanced in support of the existence of this association have been so inadequate, that the majority of thinkers have regarded the doctrine itself, maintained as it has been with so much zeal by Gall and his followers, to be little more than a theory, no doubt probable enough, but deficient in that solid basis of proof which alone could warrant its acceptance on any higher ground. But it has recently been confidently asserted that evidence is at last forthcoming that the organ of one faculty, the faculty of articulate language, has now been discovered. Still, the alleged discovery, though it were established, would give only qualified support to the phrenological view just referred to, as, contrary to all preconceived notions derived from the bilateral symmetry of the brain, the supposed organ is declared to be situated on its left side alone. Conclusions of so weighty moment evidently require that the validity of their premises should be thoroughly tested; and it is in the hope that I may be able in some degree to show how far they are trustworthy, that I have ventured to bring the facts and considerations embodied in the following paper under the notice of this Society.