taining their general laws. By pursuing this plan fteadily, they have, in the course of the two laft 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 metaphysical speculations already mentioned. Of the importance of thefe, as a separate branch of ftudy, 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 utmost 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 questions 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 spread over the body, by diffufion; are queftions perfectly analogous to thofe which Metaphyficians have started on the fubject of matter. It is unneceffary 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 obvioufly 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

4

their phenomena are produced, have no neceffary connexion with our inquiries concerning the laws, according to which these phenomena take place.-Whether (for example) the cause 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 diftance, according to a certain law. In like manner, in the ftudy 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 fuggest 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 leaft 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, thefe facts are blended with speculations 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 philosophy of mind into fome degree of difcredit; nor will ever its real value be generally acknowledged, till the distinction I have endeavoured to illustrate, be understood, and attended to, by those who fpeculate on the subject. By confining their attention to the fenfible qualities of body, and to the fenfible phenomena it exhibits, we know what difcoveries natural philofophers have made and if the labours of Metaphysicians shall 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 phyfical inquirers fhould think of again employing themselves in fpeculations about the nature of matter, instead of attempting to ascertain its sensible properties and laws, (and of late there feems to be fuch a tendency among fome of the followers of Bofcovich,) they will foon involve themfelves in an inextricable labyrinth, and the first principles of phyfics will be rendered as myfterious and chimerical, as the pneumatology of the fchool-men.

The little progrefs which has hitherto been made in the philofophy of mind, will not appear surprising 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

and chemical fubjects which are daily offered to the public, whether it be yet understood fo completely as is commonly imagined; and whether a fuller illuftration of the rules of philofophifing, than Bacon or his followers have given, might not be useful, even to phyfical inquirers.

When we reflect, in this manner, on the fhortness of the period during which natural philosophy has been fuccefsfully cultivated; and, at the fame time, confider how open to our examination the laws of matter are, in comparison of those which regulate the phenomena of thought, we shall neither be difpofed to wonder, that the philosophy of mind fhould ftill remain in its infancy, nor be difcouraged in our hopes concerning its future progress. The excellent models of this fpecies of investigation, which the writings of Dr. Reid exhibit, give us ground to expect that the time is not far diftant, when it fhall affume that rank which it is entitled to hold among the fciences.

It would probably contribute much to accelerate the progress of the philofophy of mind, if a distinct explanation were given of its nature and object; and if some general rules were laid down, with refpect to the proper method of conducting the ftudy of it. To this subject, however, which is of fufficient extent to furnish matter for a feparate work, I cannot attempt to do juftice at prefent; and fhall therefore confine myself to the illuftration of a few fundamental principles, which it will be of effential importance for us to keep in view in the following inquiries.

Upon a flight attention to the operations of our own minds, they appear to be fo complicated, and fo infinitely diverfified,

diverfified, that it feems to be impoffible to reduce them to any general laws. In confequence, however, of a more accurate examination, the profpect clears up; and the phenomena, which appeared, at first, to be too various for our comprehenfion, are found to be the refult of a comparatively fmall number of fimple and uncompounded faculties, or of fimple and uncompounded principles of action. Thefe faculties and principles are the general laws of our conflitution, and hold the fame place in the philofophy of mind, that the general laws we investigate in phyfics, hold in that branch of fcience. In both cafes, the laws which nature has established, are to be inveftigated only by an examination of facts; and in both cafes, a knowledge of thefe laws leads to an explanation of an infinite number of phenomena.

In the investigation of phyfical laws, it is well known, that our inquiries must always terminate in fome general fact, of which no account can be given, but that fuch is the conftitution of nature. After we have established, for example, from the aftronomical phenomena, the univerfality of the law of gravitation,

it

may ftill be asked, whether this law implies the conftant agency of mind; and (upon the fuppofition that it does) whether it be probable that the Deity always operates immediately, or by means of fubordinate instruments? But thefe queftions, however curious, do not fall under the province of the natural philofopher. It is fufficient for his purpose, if the univerfality of the fact be admitted.

The cafe is exactly the fame in the philosophy of mind. When we have once afcertained a general

fact;