sions which are open to the examination of all men capable of exercising the power of Reflection; and, therefore, scientific distinctness requires, that these two different classes of propositions should not be confounded together under one common name. For my own part, I have no scruple to say, that I consider the physiological problem in question, as one of those which are likely to remain for ever among the arcana of nature; nor am I afraid of being contradicted by any competent and candid judge, how sanguine soever may be his hopes concerning the progress of future discovery, when I assert, that hitherto it has completely eluded all the efforts which have been made towards its solution. As to the metaphysical romances above alluded to, they appear to me, after all the support and illustration which they have received from the ingenuity of Hartley, of Priestley, and of Darwin, to be equally unscientific in the design, and uninteresting in the execution; destitute, at once, of the sober charms of Truth, and of those. imposing attractions which Fancy, when united to Taste, can lend to Fiction. In consequence of the unbounded praise bestowed upon them by some whose opinions are entitled to much respect, I have repeatedly begun the study of them anew, suspecting that I might be under the influence of some latent and undue prejudice against this new mode of philosophizing, so much in vogue at present in England; but notwithstanding the strong predilection which I have always felt for such pursuits, my labour has uniformly ended in a sentiment of regret, at the time and attention which I had misemployed in so hopeless and so ungrateful a task.

Mr. Locke, although he occasionally indulges himself in hints and conjectures, somewhat analogous to those of Hartley and Darwin, seems to have been perfectly aware how foreign such speculations are to the genuine Philosophy of the Human Mind. In the second paragraph of the Introduction to his Essay, he thus expresses himself:-" This, therefore, being my purpose, to inquire into the original, certainty, and extent of human knowledge; together with the grounds and degrees of belief, opinion, and assent, I shall not at present meddle with

the physical consideration of the Mind, or trouble myself to examine wherein its essence consists, or by what motions of our spirits, or alteration of our bodies, we come to have any sensation by our organs, or any ideas of our understandings; and whether these ideas do in their formation, any or all of them, depend on Matter or not. These are speculations which, however curious and entertaining, I shall decline, as lying out of my way in the design I am now upon."-It is much to be wished, that Mr. Locke had adhered invariably to this wise resolution.

I flatter myself it will not be inferred, from what has been here said of the common theories of physiologists about the causes of the intellectual phenomena, that I entertain any doubt of the intimate connexion which exists between these phenomena and the organization of the body. The great principle I am anxious to inculcate is, that all the theories which have yet been offered on this subject, are entirely unsupported by proof; and what is worse, are of such a kind, that it is neither possible to confirm nor to refute them, by an appeal to experiment or observation. That I was all along fully aware of the dependence, in our present state, of the mental operations on the sound condition of the corporeal frame, appears sufficiently from what I remarked, many years ago, concerning the laws of this connexion between mind and body, as presenting one of the most interesting objects of examination connected with the theory of human nature.1

I have been induced to caution my readers against the possibility of such a misapprehension of my meaning, by the following passage in a late publication:-"What that affection of the brain is," says Mr. Belsham, "which, by the constitution of human nature, causes Memory, we cannot absolutely ascertain. The hypothesis of Vibrations, which has already been explained, is the most probable. It is trifling to object, that if the existence of impressions on the brain could be proved, Memory would remain as unaccountable as before; all which this hypothesis pretends to, is to advance a step in tracing the 'Philosophy of the Human Mind, [supra, vol. i. pp. 52, 53, (Works, vol. ii.)]

process of the connexion between external objects and mental feelings."—" It is curious to observe," the same author continues, “that Dr. Reid, after starting several objections against the commonly received hypothesis, is obliged to admit, that many well-known facts lead us to conclude, that a certain constitution or state of the brain is necessary to Memory."

On this passage I shall offer only two remarks: The first is, that, notwithstanding Mr. Belsham's zeal for Hartley's Theory of Vibrations, he confesses explicitly, that "we cannot absolutely ascertain what that affection of the brain is, which, by the constitution of human nature, causes Memory ;" and that, "the theory of Vibrations, though more probable than some others, is still but a hypothesis." Secondly, that Mr. Belsham, after making this explicit acknowledgment, is nevertheless pleased to insinuate, that all who presume to object to this particular hypothesis, are bound by their own principles to assert, that Memory has no dependence whatever on the state of the brain. Where the inconsistency lies in Dr. Reid's admission, that a certain constitution or state of the brain is necessary to Memory, after he had stated some objections. against the commonly received theories, I am at a loss to perceive. Indeed, I should be glad to know what philosopher, ancient or modern, has ever yet asserted that Memory is not liable to be injured by such affections of the brain as are produced by intemperance, disease, old age, and other circumstances which disturb the bodily mechanism. The philosophical inference, however, from this concession is, not that the hypothesis of Dr. Hartley, or the hypothesis of Mr. Belsham, must necessarily be true; but that, laying aside all hypotheses, we should apply ourselves to collect such facts as may lead us, in due time, to the only satisfactory conclusions we have much chance of ever forming concerning the connexion between Mind and Body—the discovery of some of the general laws by which this connexion is regulated.

In offering these strictures on the physiological metaphysics of the present day, it is proper for me, at the same time, to observe, that I object to it merely as an idle waste of labour

and ingenuity, on questions to which the human faculties are altogether incompetent; and not because I consider any of the theories, to which it has given birth, as standing in the way of my own doctrines. The facts which I wish to ascertain rest on their own proper evidence,-an evidence which would remain entire and unshaken, although a demonstration should be produced in favour of the Animal Spirits of Descartes, or of the Vibrations of Hartley; and which would not gain the slightest accession of strength, if both these hypotheses were to fall into the contempt they deserve. The circumstance which peculiarly characterizes the inductive Science of the Mind is, that it professes to abstain from all speculations concerning its nature and essence, confining the attention entirely to phenomena, which every individual has it in his power to examine for himself, who chooses to exercise the powers of his understanding. In this respect, it differs equally in its scope, from the pneumatological discussions concerning the seat of the Soul, and the possibility or the impossibility of its bearing any relation to Space or to Time, which so long gave employment to the subtilty of the Schoolmen,—and from the physiological hypotheses which have made so much noise at a later period, concerning the mechanical causes on which its operations depend. Compared with the first it differs, as the inquiries of Galileo concerning the laws of moving bodies differ from the disputes of the ancient Sophists concerning the existence and the nature of Motion. Compared with the other, the difference is analogous to what exists between the conclusions of Newton about the law of Gravitation, and his query concerning the invisible ether, of which he supposed it might possibly be the effect. be worth while to add in passing, that the diversity of opinion among Newton's followers with respect to the verisimilitude of this query, while they have unanimously acquiesced in the physical conclusions of their master, affords an instructive proof how little the researches of inductive science are liable to be influenced by the wanderings of Imagination in those regions which human reason is not permitted to explore. Whatever our opinion concerning the unknown physical or

It may

metaphysical cause of gravitation may be, our reasonings concerning the System of Nature will be equally just, provided only we admit the general fact, that bodies tend to approach each other with a force varying with their mutual distances, according to a certain law. The case is precisely similar with respect to those conclusions concerning the Mind, to which we are fairly led by the method of Induction. They rest upon a firm and indisputable basis of their own, and (as I have elsewhere remarked) are equally compatible with the metaphysical creeds of the Materialist and of the Berkeleian.1

II. Intimately connected with the physiological hypothesis of the Hartleian school, is their metaphysical theory of Association, from which single principle they boast to have explained synthetically all the phenomena of the Mind. In Dr. Priestley's Remarks on Reid's Inquiry, there is an attempt to turn into ridicule, by what the author calls a Table of Dr. Reid's Instinctive Principles, the application of the Inductive Logic to these phenomena. How far this Table is faithfully extracted from Dr. Reid's book, it is unnecessary to consider at

1 [Elements, &c., vol. i. p. 49.] The hypothesis which assumes the existence of a subtle fluid in the nerves, propagated by their means from the brain to the different parts of the body, is of great antiquity, and is certainly less repugnant to the general analogy of our frame, than that by which it has been supplanted. How very generally it once prevailed, may be inferred from the adoption into common speech of the phrase animal spirits, to denote that unknown cause which (according to Johnson's definition) "gives vigour or cheerfulness to the mind;"- —a phrase for which our language does not, at this day, afford a convenient substitute. The late Dr. Alexander Monro (one of the most cautious and judicious of medical inquirers) speaks of it as a fact which appeared to him to be almost indisputable. "The existence of a liquid in the cavities of the nerves, is supported by

little short of demonstrative evidence." See some observations of his, published by Cheselden in his Anatomy.

The hypothesis of Vibrations first attracted public notice in the writings of Dr. William Briggs. It was from him that Sir Isaac Newton derived his anatomical knowledge; along with which he appears plainly, from his Queries, to have imbibed also some of the physiological theories of his preceptor.

In the Monthly Review for 1808, I observe the following passage:-" For the partiality which he (Dr. Cogan) shews to Dr. Reid, we may easily account, as being a just tribute to the ingenuity and industry of that writer, and to the numerous valuable observations which enrich his works, unconnected with his crude hypothesis on the subject of the Human Mind."

In what part of Dr. Reid's writings is this crude hypothesis proposed?