Of the more immediate, or, as it is generally termed, the proximate cause of this disease, I profess to know nothing. Whenever the functions of the brain shall be fully understood, and the use of its different parts ascertained, we may then be enabled to judge, how far disease, attacking any of these parts, may increase, diminish, or otherwise alter its functions. But this appears a degree of knowledge which we are not likely soon to attain. It seems, however, not improbable that the only source from whence the most copious and certain information can be drawn, is a laborious attention to the particular appearances which morbid states of this organ may present. From the preceding dissections of insane persons, it may be inferred, that madness has always been connected with disease of the brain, and of its membranes. These cases have not been selected from a variety of others, but comprize the entire number which have fallen under my observation. Having no particular theory to build up, they have been related purely for the advancement of science and of truth. It may be a matter affording much diversity of opinion, whether these morbid appearances of the brain be the cause or the effect of madness: it may be observed, that they have been found in all states of the disease. When the brain has been injured from external violence, its functions have been generally impaired if inflammation of its substance, or more delicate membranes has ensued. The same appearances have for the most part been detected when patients have died of phrenitis, or in the delirium of fever: in these instances the derangement of the intellectual functions appears evidently to have been caused by the inflammation. If in mania the same appearances be found, there will be no necessity of calling in the aid of other causes to account for the effect; indeed it would be difficult to discover them. Those who entertain an opposite opinion, are obliged to suppose, _a disease of the mind_. Such a morbid affection, from the limited nature of my powers, perhaps I have never been able to conceive. Possessing, however, little knowledge of metaphysical controversy, I shall only offer a few remarks upon this part of the subject, and beg pardon for having at all touched it. Perhaps it is not more difficult to suppose that matter peculiarly arranged may _think_, than to conceive the union of an immaterial being with a corporeal substance. It is questioning the infinite wisdom and power of the Deity to say, that he does not, or cannot arrange and organize matter so that it shall think. When we find insanity, as far as has hitherto been observed, uniformly accompanied with disease of the brain, is it not more just to conclude, that such organic affection has produced this incorrect association of ideas, than that a being, which is immaterial, incorruptible and immortal, should be subject to the gross and subordinate changes which matter necessarily undergoes?