in the same manner. In other cases, the patient seems to invent names, using words which to a stranger are quite unintelligible; but he always uses them in the same sense, and his immediate attendants come to understand what he means by them.

Another remarkable modification of this condition of the mental powers is found in those cases in which there is loss of the recollection of a particular period. A clergyman, mentioned by Dr. Beattie, on recovering from an apoplectic attack, was found to have lost the recollection of exactly four years; every thing that occurred before that period he remembered perfectly. He gradually recovered, partly by a spontaneous revival of his memory, and partly by acquiring a knowledge of the leading events of the period. A young lady who was present at a late catastrophe in Scotland, in which many people lost their lives by the fall of the gallery of a church, escaped without any injury, but with the complete loss of the recollection of any of the circumstances; and this extended, not only to the accident, but to every thing that had occurred to her for a certain time before going to church. A lady whom I attended some years ago in a protracted illness, in which her memory became much impaired, lost the recollection of a period of about ten or twelve years, but spoke with perfect consistency of things as they stood before that time.

As far as I have been able to trace it, the principle in such cases seems to be, that when the memory is impaired to a certain degree, the loss of it extends backwards to some event or some period by which a particularly deep impression had been made upon the mind. In the lady last mentioned, for instance, the period of which she lost the recollection was that during which she had resided in Edinburgh, and it extended back to her removal from another city in which she had lived for many years. During her residence in the latter, she had

become the mother of a large family, and other events had occurred likely to make a deep impression on her mind. The period of her residence in Edinburgh had been uniform and tranquil, and without any occurrence calculated to excite much attention in a person of rather slender mental endowments. I do not know whether we can give a similar explanation of cases in which the loss of memory has extended only to particular subjects; namely, by supposing that these subjects had been more slightly impressed upon the mind than those which were retained. A gentleman is mentioned by Dr. Beattie, who, after a blow on the head, lost his knowledge of Greek, and did not appear to have lost any thing else.

While we thus review the manner in which the manifestations of mind are affected, in certain cases, by diseases and injuries of the brain, it is necessary that we should refer briefly to the remarkable instances in which the brain has been extensively diseased without the phenomena of mind being impaired in any sensible degree. This holds true both in regard to the destruction of each individual part of the brain, and likewise to the extent to which the cerebral mass may be diseased or destroyed. In another work I have mentioned various cases which illustrate this fact in a very striking manner; particularly the case of a lady in whom one-half of the brain was reduced to a mass of disease; but who retained all her faculties to the last, except that there was an imperfection of vision, and had been enjoying herself at a convivial party in the house of a friend a few hours before her death. A man, mentioned by Dr. Ferriar, who died of an affection of the brain, retained all his faculties entire till the very moment of death, which was sudden: on examining his head, the whole right hemisphere,-that is, one-half of his brain,-was found destroyed by sup

puration. In a similar case recorded by Diemerbroek, half a pound of matter was found in the brain; and in one by Dr. Heberden, there was half a pound of water. A man, mentioned by Mr. O'Halloran, suffered such an injury of the head that a large portion of the bone was removed on the right side; and extensive suppuration having taken place, there was discharged at each dressing, through the opening, an immense quantity of matter mixed with large masses of the substance of the brain. This went on for seventeen days, and it appears that nearly one-half of the brain was thrown out mixed with the matter; yet the man retained all his intellectual faculties to the very moment of dissolution; and through the whole course of the disease, his mind maintained uniform tranquillity. These remarkable histories might be greatly multiplied if it were required, but at present it seems only necessary to add the very interesting case related by Mr. Marshall. It is that of a man who died with a pound of water in his brain, after having been long in a state of idiocy, but who, a very short time before death, became perfectly rational.

The facts which have been thus briefly referred to present a series of phenomena of the most rer markable kind, but on which we cannot speculate in the smallest degree without advancing beyond the sphere of our limited faculties; one thing, however, is certain, that they give no countenance to the doctrine of materialism, which some have presumptuously deduced from a very partial view of the influence of cerebral disease upon the manifestations of mind. They show us, indeed, in a very striking manner, the mind holding intercourse with the external world through the medium of the brain and nervous system; and, by certain diseases of these organs, they show this intercourse impaired or suspended; but they show nothing more. In particular, M

they warrant nothing in any degree analogous to those partial deductions which form the basis of materialism. On the contrary, they show us the brain injured and diseased to an extraordinary extent without the mental functions being affected in any sensible degree. They show us, further, the manifestations of mind obscured for a time, and yet reviving in all their original vigour, almost in the very moment of dissolution. Finally, they exhibit to us the mind, cut off from all intercourse with the external world, recalling its old impressions, even of things long forgotten; and exercising its powers on those which had long ceased to exist, in a manner totally irreconcilable with any idea we can form of a material function.

SECTION II.

ABSTRACTION.

BY ABSTRACTION we separate various facts from each other, and examine them individually. We separate, for example, the qualities of a substance, and contemplate one of them apart from the rest. This act of the mind is employed in two processes of the utmost importance. By the one, we examine a variety of objects, select the properties in which certain numbers of them agree, and thus arrange them into classes, genera, and species. By the other, we take a more comprehensive view of an extensive collection of facts, and select one which is common to the whole. This we call generalizing, or deducing a general fact or general principle; and the process is of extensive application in all philosophical inquiries. The particular points to be attended to

in conducting it will come under view in another part of our subject. The most important is, that the fact assumed as general really belongs to all the individual instances, and has not been deduced from the examination of only a part of them.

There have been disputes among writers on the science of mind, whether abstraction is to be considered as a distinct mental operation, or is referable to judgment. But I have already stated that my object in this outline is to avoid all such discussions, and to allude simply to the actual processes of the mind in a practical view. One thing at least is clear, namely, that our abstractions must be corrected by reason, the province of which is to judge whether the process is performed correctly, and on sound principles. This, however, is distinct from the primary act of the mind to which I now apply the term abstraction, which is simply the power of contemplating one property of a substance apart from its other properties. It thus disjoins things which by nature are intimately united, and which cannot be separated in any other manner. Reason does not appear to be immediately concerned in this, though it is most closely connected with the purposes to which the process is afterward applied; namely, classifying substances according to a certain agreement of properties, and fixing upon those which are common to all the individuals of a numerous series, in the act of generalizing, or deducing a general fact or general principle.

I have formerly alluded to a period in the science of mind, when our ideas of external things were supposed to be certain actual essences, separated from the substances and conveyed to the thinking principle. In connexion with this theory there arose a controversy, whether, when we perform the mental act of generalizing, there exists in nature any essence corresponding to a general idea; or whether, in generalizing, we merely make use of an abstract term: whether, for example, in using the word man