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cellent prelate appears to have given every encouragement; and I have been told by the best authority, that he was accustomed to say, that his reasonings had been nowhere better understood than by this club of young Scotsmen.* The ingenious Dr. Wallace, author of the Discourse on the Numbers of Mankind, was one of the leading members ; and with him were associated several other individuals, whose names are now well known and honorably distinguished in the learned world. Mr. Hume's Treatise of Human Nature, which was published in 1739, affords sufficient evidence of the deep impression which Berkeley's writings had left upon his Mind; and to this juvenile essay of Mr. Hume's may be traced the origin of the most important metaphysical works which Scotland has since produced.
It is not, however, my intention to prosecute farther, at present, the history of Scotish philosophy. The subject may be more conveniently, and I hope advantageously resumed, after a slight review of the speculations of some English and French writers, who, while they professed a general acquiescence in the doctrines of Locke, have attempted to modify his fundamental principles in a manner totally inconsistent with the views of their master. The remarks which I mean to offer on the modern French school will afford me, at the same time, a convenient opportunity of introducing some strictures on the metaphysical systems which have of late prevailed in other parts of the Continent.
The English writers to whom I have alluded in the last paragraph, I shall distinguish by the title of Dr. Hartley's School; for although I by no means consider this person as the first author of any of the theories commonly ascribed to him (the seeds of all of them having
• The authority I here allude to is that of my old friend and preceptor, Dr. John Stevenson, who was himself a member of the Rankenian Club, and who was accustomed for many years to mention this fact in his Academical Prelections. VOL. VI.
been previously sown in the university where he was educated), it was nevertheless reserved for him to combine them together, and to exhibit them to the world in the imposing form of a system.
Among the immediate predecessors of Hartley, Dr. Law, afterwards Bishop of Carlisle, seems to have been chiefly instrumental in preparing the way for a schism among Locke's disciples. The name of Law was first known to the public by an excellent translation, accompanied by many learned, and some very judicious notes, of Archbishop King's work on the Origin of Evil; a work of which the great object was to combat the Optimism of Leibnitz, and the Manicheism imputed to Bayle. In making this work more generally known, the translator certainly rendered a most acceptable and important service to the world, and, indeed, it is upon this ground that his best claim to literary distinction is still founded.* In his own original speculations, he is weak, paradoxical, and oracular; f affecting, on all occasions, the most profound veneration of the opinions of Locke, but much more apt to attach himself to the errors and oversights of
King's argument in proof of the prevalence in this world, both of Natural and Moral Good, over the corresponding Evils, has been much and deservedly admired; nor are Law's Notes on this head entitled to less praise. Indeed, it is in this part of the work that both the author and his commentator appear, in my opinion, to the greatest advantage.
† As instances of this I need only refer to the first and third of his Notes on King; the former of which relates to the word substance ; and the latter to the dispute between Clarke and Leibnitz concerning space. His reasonings on both subjects are obscured by an affected use of hard and unmeaning words, ill becoming so devoted an admirer of Locke. The same remark inay be extended to an Inquiry into the Ideas of Space and Time, published by Dr. Law in 1734.
The result of Law's speculations on Space and Time is thus stated by himself: “ That our ideas of them do not imply any external ideatum or objective reality; that these ideas (as well as those of infinity and number) are universal or abstract ideas, existing under that formality no where but in the mind; nor affording a proof of any thing, but of the power which the mind has to form them.” (Law's Trans. of King, p. 7, 4th edit.) This language, as we shall afterwards see, approaches very nearly to that lately introduced by Kant. Dr. Law's favorite author might have cautioned him against such jargon. (See Essay on the Human Understanding, Book II. Chap. xiii. $ 17, 18.)
The absurd application of the scholastic word substance to empty space; an absurdity in which the powerful mind of Gravesande acquiesced many years after the publication of the Essay on Human Understanding, has probably contributed not a little to force some authors into the opposite extreme of maintaining, with Leibnitz and Dr. Law, that our idea of space does not imply any external ideatum or objective reality. Gravesande's words are these : “ Substantiæ sunt aut cogitantes, aut non cogitantes; cogitantes duas novimus, Deum et Mentem nostram ; præter has et alias dari in dubium non revocamus. Duæ etiam substantiæ, quæ non cogitant, nobis notæ sunt, Spatium et Corpus.”—Gravesande, Introd. ad Philosophiam, & 19.
that great man, than to enter into the general spirit of his metaphysical philosophy.
To this translation, Dr. Law prefixed a Dissertation concerning the Fundamental Principle of Virtue, by the Reverend Mr. Gay; a performance of considerable ingenuity; but which would now be entitled to little notice, were it not for the influence it appears to have had in suggesting to Dr. Hartley the possibility of accounting for all our intellectual pleasures and pains, by the single principle of the Association of Ideas. We are informed by Dr. Hartley himself, that it was in consequence of hearing some account of the contents of this dissertation, he was first led to engage in those inquiries which produced his celebrated Theory of Human Nature.
The other principle on which this theory proceeds (that of the vibrations and vibratiuncles in the medullary substance of the brain) is also of Cambridge origin. It occurs in the form of a query in Sir Isaac Newton's Optics; and a distinct allusion to it, as a principle likely to throw new light on the phenomena of mind, is to be found in the concluding sentence of Smith's Harmonics.
Very nearly about the time when Hartley's Theory appeared, Charles Bonnet of Geneva published some speculations of his own, proceeding almost exactly on the same assumptions. Both writers speak of vibrations (ébranlemens) in the nerves; and both of them have recourse to a subtile and elastic ether, co-operating with the nerves in carrying on the communication between soul and body.* This fluid Bonnet conceived to be contained in the nerves, in a manner analogous to that in which the electric fluid is contained in the solid bodies which conduct it ; differing in this respect from the Cartesians as well as from the ancient physiologists, who considered the nerves as hollow tubes, or pipes, within which the animal spirits were included. It is to this elastic ether that Bonnet ascribes the vibrations of which he supposes the nerves to be susceptible ; for the nerves themselves (he justly observes) have no resemblance to
* Essai Analytique de l’Ame, Chap. v. See also the additional notes on the first chapter of the seventh part of the Contemplation de la Nature.
the stretched cords of a musical instrument.* Hartley's Theory differs in one respect from this, as he speaks of vibrations and vibratiuncles in the medullary substance of the brain and nerves. He agrees, however, with Bonnet in thinking, that to these vibrations in the nerves the cooperation of the ether is essentially necessary; and, therefore, at bottom the two hypotheses may be regarded as in substance the same. As to the trifling shade of difference between them, the advantage seems to me to be in favor of Bonnet.
Nor was it only in their Physiological Theories concerning the nature of the union between soul and body, that these two philosophers agreed. On all the great articles of metaphysical theology, the coincidence between their conclusions is truly astonishing. Both held the doctrine of Necessity in its fullest extent; and both combined with it a vein of mystical devotion, setting at defiance the creeds of all established churches. The intentions of both are allowed, by those who best knew them, to have been eminently pure and worthy; but it cannot be said of either, that his metaphysical writings have contributed much to the instruction or to the improvement of the public. On the contrary, they have been instrumental in spreading a set of speculative tenets very nearly allied to that sentimental and fanatical modification of Spinozism, which, for many years past, has prevailed so much, and produced such mischievous effects in some parts of Germany.
* “ Mais les nerfs sont mols, ils ne sont point tendus comme les cordes d'un instrument; les objets y exciteroient-ils donc les vibrations analogues à celles d'un corde pincée? Ces vibrations se communiqueroient-elles à l'instant au siège de l'âme ? La chose paroit difficile à concevoir. Mais si l'on admet dans les nerfs un fluide dont la subtilité et l'élasticité approche de celle de la lumière ou de l'éther, on expliquera facilement par le secours de ce fluide, et la célérité avec laquelle les impressions se communiquent à l'âme, et celles avec laquelle l'âme éxécute tant d'opé. rations différentes.” (Essai Anal. Chap. v.)
“ Au reste, les physiologistes qui avoient cru que les filets nerveux étoient solides, avoient cédé à des apparences troinpeuses. Ils vouloient d'ailleurs faire osciller les nerfs, pour rendre raison des sensations, et les nerfs ne peuvent osciller. Ils sont mous, et nullement élastiques. Un nerf coupé ne se retire point. C'est le Auide invisible que les nerfs renferment, qui est doué de cette élasticité qu'on leur attribuoit, et d'une plus grand élasticité encore.” (Contemp. de la Nature, VII Partie, Chap. i. Notes at the end of the chapter.)
M. Quesnai, the celebrated author of the Economical System, has expressed himself to the same purpose concerning the supposed vibrations of the nerves: “ Plusieurs physiciens ont pensé que le seul ébranlement des nerfs, causé par les objets qui touchent les organes des corps, suffit pour occasioner le mouvement et le sentiment dans les parties où les nerfs sont ébranlés. Ils se représentent les nerfs comme des cordes fort tendus, qu’un léger contact met en vibration dans toute leur étendue. Des philosophes, peu instruits en anatomie, ont pu se former une telle idée.
Mais cette tension qu'on suppose dans les nerfs, et qui les rend si susceptibles d'ébranlement et de vibration, est si grossièrement imaginée qu'il seroit ridicule de s'occuper sérieusement à la réfuter. (Econ. Animale, sect. c. 13.)
As this passage from Quesnai is quoted by Condillac, and sanctioned by his authority (Traité des Animaux, Chap. iii.), it would appear that the hypothesis which supposes the nerves to perform their functions by means of vibrations was going fast into discredit, both among the metaphysicians and the physiologists of France, at the very time when it was beginning to attract notice in England, in consequence of the vis. ¡onary speculations of Hartley.
But it is chiefly by his application of the associating principle to account for all the mental phenomena that Hartley is known to the world ; and upon this I have nothing to add to what I have already stated in another work. (Phil. Essays, Essay IV.) His Theory seems to be already fast passing into oblivion; the temporary popularity which it enjoyed in this country having, in a great measure, ceased with the life of its zealous and indefatigable apostle, Dr. Priestley.*
It would be unfair, however, to the translator of Archbishop King, to identify his opinions with those of Hartley and Priestley. The zeal with which he contends for man's free agency is sufficient, of itself, to draw a strong line of distinction between his Ethical System and theirs. (See his Notes on King, passim.) But I must be allowed to say of him, that the general scope of his writings tends, in common with that of the two other metaphysicians, to depreciate the evidences of Natural Religion, and more especially to depreciate the evidences which the light of nature affords of a life to come; "a doctrine equally necessary to comfort the weakness, and to support our lofty ideas of the grandeur of human nature ;” † and of which it seems hard to confine exclusively the knowledge to that portion of mankind
Dr. Priestley's opinion of the merits of Hartley's work is thus stated by himself: Something was done in this field of knowledge by Descartes, very much by Mr. Locke, but most of all by Dr. Hartley, who has thrown more useful light upon the theory of the mind, than Newton did upon the theory of the natural world.”— (Remarks on Reid, Beattie, and Oswald, p. 2. Lond. 1774.)
† Smith's Theory of Moral Sentiments, 6th Ed. Vol. I. pp. 325, 326.
Dr. Law's doctrine of the sleep of the soul, to which his high station in the church could not fail to add much weight in the judgment of many, is, I believe, now universally adopted by the followers of Hartley and Priestley ; the theory of vibrations being evidently inconsistent with the supposition of the soul's being able to exercise her powers in a separate state from the body.