have for the exiftence of body; nay, if there be any difference between the two cafes, that we have stronger evidence for it; inafmuch as the one is fuggefted to us by the subjects of our own consciousness, and the other merely by the objects of our perceptions: and in this light, undoubtedly, the fact would appear to every person, were it not, that, from our earliest years, the attention is engroffed with the qualities and laws of matter, an acquaintance with which is abfolutely neceffary for the prefervation of our animal exiftence. Hence it is, that these phenomena occupy our thoughts more than thofe of mind; that we are perpetually tempted to explain the latter by the analogy of the former, and even to endeavour to refer them to the fame general laws; and that we acquire habits of inattention to the fubjects of our confcioufnefs, too ftrong to be afterwards furmounted, without the moft perfe vering industry. If the foregoing obfervations be well founded, they establish the distinction between mind and matter, without any long procefs of metaphyfical reafoning*: for if our notions of both are merely relative; if we know the one, only by fuch fenfible qualities as extenfion, figure, and folidity; and the other, by fuch operations as fenfation, thought, and volition; we are certainly entitled to fay, that matter and mind, confidered as objects of human ftudy, are effentially different; the science of the former refting ultimately on the phenomena exhibited to our fenfes; that of the latter, on the phenomena of which we are confcious. Instead, therefore, of objecting to the scheme of mate. * See Note [A], at the end of the volume. rialism, rialism, that its conclufions are falfe, it would be more accurate to fay, that its aim is unphilofophical. It proceeds on a misapprehenfion of the proper object of fcience; the difficulty which it profeffes to remove being manifeftly placed beyond the reach of our fa culties. Surely, when we attempt to explain the nature of that principle which feels and thinks and wills, by faying, that it is a material fubftance, or that it is the refult of material organization, we impose on ourselves by words; forgetting, that matter as well as mind is known to us by its qualities and attributes alone, and that we are totally ignorant of the effence of either *. As all our knowledge of the material world is derived from the information of our fenfes, Natural philofophers have, in modern times, wifely abandoned to Metaphyficians, all fpeculations concerning the nature of that fubftance of which it is compofed; concerning the poffibility or impoffibility of its being created; concerning the efficient caufes of the changes which take place in it; and even concerning the reality of its existence, independent of that of percipient beings: and have confined themselves to the humbler province of obferving the phenomena it exhibits, and of afcer Some Metaphyficians, who appear to admit the truth of the foregoing reafoning, have farther urged, that for any thing we can prove to the contrary, it is poffible, that the unknown fubftance which has the qualities of extenfion, figure, and colour, may be the fame with the unknown fubftance which has the attributes of feeling, thinking, and willing. But befides that this is only an hypothefis, which amounts to nothing more than a mere poffibility, even if it were true, it would no more be proper to fay of mind, that it is material, than to fay of body, that it is fpiritual. taining their general laws. By pursuing this plan fteadily, they have, in the course of the two last centuries, formed a body of science, which not only does honour to the human understanding, but has had a most important influence on the practical arts of life.This experimental philofophy, no one now is in danger of confounding with the metaphyfical fpeculations already mentioned. Of the importance of these, as a separate branch of study, it is poffible that fome may think more favourably than others; but they are obviously different in their nature, from the investigations of phyfics; and it is of the utmoft confequence to the evidence of this laft fcience, that its principles fhould not be blended with thofe of the former. A fimilar diftinction takes place among the queftions which may be stated relative to the human mind. Whether it be extended or unextended; whether or not it has any relation to place; and (if it has) whether it refides in the brain, or be fpread over the body, by diffufion; are questions perfectly analogous to thofe which Metaphyficians have started on the fubject of matter. It is unnecessary to inquire, at prefent, whether or not they admit of anfwer. It is fufficient for my purpose to remark, that they are as widely and obviously different from the view, which I propose to take, of the human mind in the following work, as the reveries of Berkeley concerning the nonexistence of the material world, are from the conclufions of Newton, and his followers.--It is farther evident, that the metaphyfical opinions, which we may happen to have formed concerning the nature either of body or of mind, and the efficient caufes by which their phenomena are produced, have no neceffary con. nexion with our inquiries concerning the laws, according to which these phenomena take place. Whether (for example) the caufe of gravitation be material or immaterial, is a point about which two Newtonians may differ, while they agree perfectly in their physical opinions. It is fufficient, if both admit the general fact, that bodies tend to approach each other, with a force varying with their mutual distance, according to a certain law. In like manner, in the study of the human mind, the conclufions to which we are led, by a careful examination of the phenomena it exhibits, have no neceffary connexion with our opinions concerning its nature and effence. That when two fubjects of thought, for inftance, have been repeatedly prefented to the mind in conjunction, the one has a tendency to fuggeft the other, is a fact of which I can no more doubt, than of any thing for which I have the evidence of my fenses; and it is plainly a fact totally unconnected with any hypothefis concerning the nature of the foul, and which will be as readily admitted by the materialist as by the Berkeleian. Notwithstanding, however, the reality and importance of this diftinction, it has not hitherto been fufficiently attended to, by the philofophers who have treated of the human mind. Dr. Reid is perhaps the only one who has perceived it clearly, or at least who has kept it steadily in view, in all his inquiries. In the writings, indeed, of feveral other modern Metaphyficians, we meet with a variety of important and wellafcertained facts; but, in general, these facts are blended with fpeculations upon fubjects, which are placed beyond the reach of the human faculties. It is this mixture of fact, and of hypothefis, which has brought the philofophy of mind into fome degree of difcredit; nor will ever its real value be generally acknowledged, till the diftinction I have endeavoured to illustrate, be understood, and attended to, by those who fpeculate on the fubject. By confining their attention to the fenfible qualities of body, and to the fenfible phenomena it exhibits, we know what difcoveries natural philosophers have made: and if the labours of Metaphyficians fhall ever be rewarded with fimilar fuccefs, it can only be, by attentive and patient reflection on the fubjects of their own consciousness. I cannot help taking this opportunity of remarking, on the other hand, that if physical inquirers fhould think of again employing themselves in fpeculations about the nature of matter, inftead of attempting to afcertain its fenfible properties and laws, (and of late there seems to be fuch a tendency among some of the followers of Bofcovicti,) they will foon involve themfelves in an inextricable labyrinth, and the first principles of phyfics will be rendered as mysterious and chimerical, as the pneumatology of the school-men. The little progrefs which has hitherto been made in the philofophy of mind, will not appear furprising to those who have attended to the hiftory of natural knowledge. It is only fince the time of Lord Bacon, that the study of it has been profecuted with any degree of fuccefs, or that the proper method of conducting it has been generally understood. There is even some reason for doubting, from the crude fpeculations on medical and |