this, that experience, in the acceptation in which Locke and his followers profess to understand it, can inform us of nothing but what has actually fallen under the retrospect of memory.-Of the truth and importance of these considerations, no philosopher seems to have been fully aware, previous to Mr. Hume. "As to past experience," he observes, "it can be allowed to give direct and certain information of those precise objects only, and that precise period of time, which fell under its cognizance; but why this experience should be extended to future times, and to other objects, this is the main question on which I would insist." * What is the proper answer to this question is of no moment to our present argument. It is sufficient, if it be granted, that experience alone does not afford an adequate explanation of the fact.

In concluding this essay, it may not be altogether useless to remark the oppsite errors which the professed followers of Bacon have committed, in studying the phenomena of matter, and those of mind. In the former where Bacon's maxim seems to hold wihout any limitation, they have frequently shown a disposition to stop short in its application; and to consider certain physical laws (such as the relation between the force of gravitation, and the distance of the gravitating bodies), as nessary truths, or truths which admitted of a proof, a priori; while, on the other hand, in the science of mind, where the same principle, when carried beyond certain limits, involves a manifest absurdity, they have attempted to extend it, without one single exception, to all the primary elements of our knowledge, and even to the generation of those reasoning faculties which form the characteristical attributes of our species.

* See Hume's essay entitled Sceptical Doubts, &c.

ESSAY FOURTH.

ON THE METAPHYSICAL THEORIES OF HARTLEY, PRIESTLEY,

AND DARWIN.

WHEN I hinted, in the preceding essay, that the doctrines prevalent in this country, with respect to the origin of our knowledge, were, in general, more precise and just than those adopted by the disciples of Condillac, I was aware that some remarkable exceptions might be alleged to the universality of my observations. Of those, indeed, who, in either part of the united kingdom, have confined their researches to the Philosophy of the Human Mind, properly so called, I do not recollect any individual of much literary eminence, who has carried Locke's principle to such an extravagant length as Diderot and Helvetius; but, from that class of our authors, who have, of late years, been attempting to found a new school, by jumbling together scholastic metaphysics and hypothetical physiology, various instances might be produced of theorists, whose avowed opinions on this elementary question, not only rival, but far surpass that of the French Materialists, in point of absurdity.

Among the authors just alluded to, the most noted are Hartley, Priestley, and Darwin; all of whom, notwithstanding the differences among them on particular points, agree nearly in their conclusions concerning the sources of our ideas. The first of these, after telling us, that "all our internal feelings, excepting our sensations, may be called ideas ;-that the ideas which resemble sensations may be called ideas of sensation, and all the rest intellectual ideas; "-adds, "that the ideas of sensation are the elements of which all the rest are compounded." In another passage he expresses his hopes, that, "by pursuing and perfecting the doctrine of association, he may some time or other, be enabled to analyse all that vast

* Hartley on Man, 4th edition, p. 2. of the Introduction. VOL. IV.

17

variety of complex ideas, which pass under the name of ideas of reflection and intellectual ideas, into their simple compounding parts; that is, into the simple ideas of sensation of which they consist." * And in a subsequent part of his work, he points out, still more explicitly, the difference between his own doctrine and that of Locke, in the following words: "It may not be amiss here to take notice how far the theory of these papers has led me to differ, in respect of logic, from Mr. Locke's excellent Essay on the Human Understanding, to which the world is so much indebted for removing prejudices and incumbrances, and advancing real and useful knowledge."

"First, then, it appears to me, that all the most complex ideas arise from sensation; and that reflection is not a distinct source, as Mr. Locke makes it."

The obvious meaning of these different passages is, that we have no direct knowledge of the operations of our own minds; nor indeed any knowledge whatsoever, which is not ultimately resolvable into sensible images.

As to Dr. Hartley's grand arcanum, the principle of association, by which he conceives that ideas of sensation may be transmuted into ideas of reflection, I have nothing to add to what I have already remarked, on the unexampled latitude with which the words association and idea are, both of them, employed, through the whole of his theory. His ultimate aim, in this part of it, is precisely the same with that of the schoolmen, when they attempted to explain, by the hypothesis of certain internal senses, how the sensible species received from external objects, are so refined and spiritualized, as to become, first, objects of memory and imagination; and, at last, objects of pure intellection. Such reveries are

certainly not entitled to a serious examination in the present age.†

*Hartley on Man, 4th edition, pp. 75, 76. † Page 360.

I do not recollect that any one has hitherto taken notice of the wonderful coincidence, in this instance, between Hartley's Theory, and that of Condillac, formerly mentioned, concerning the transformation of sensations into ideas. Condillac's earliest work (which was published in 1746, three years before Hartley's Observations on Man) is entitled Essai sur l'origine des Connoissances Humaines. Ouvrage où l'où reduit à un seul principe tout ce qui concerne l'entendement humain.

It must not, however, be concluded from these extracts, that Hartley was a decided materialist. On the contrary, after observing, that "his theory must be allowed to overturn all the arguments which are usually brought for the immateriality of the soul from the subtilty of the internal senses, and of the rational faculty,' he acknowledges candidly his own conviction, that "matter and motion, however subtly divided, or reasoned upon, yield nothing but matter and motion still; and therefore requests, that "he may not be, in any way, interpreted so as to oppose the immateriality of the soul."* I mention this in justice to Hartley, as most of his later followers have pretended, that, by rejecting the supposition of a principle distinct from body, they have simplified and perfected his theory.

With respect to Hartley's great apostle, Dr. Priestley, I am somewhat at a loss, whether to class him with materialists, or with immaterialists; as I find him an advocate, at one period of his life, for what he was then pleased to call the immateriality of matter, and, at another, for the materiality of mind. Of the former of these doctrines, to which no words can do justice but those of the author, I shall quote his own statement from his "History of Discoveries relating to Vision, Light, and Colors," first published in 1772.

"This scheme of the IMMATERIALITY OF MATTER, AS IT MAY BE CALLED, or rather the mutual penetration of

This seul principe is precisely the association of ideas. "J'ai, ce me semble," the author tells us in his introduction, " trouvé la solution de tous ces problèmes dans la liaison des idées, soit avec les signes, soit entr'elles."-In establishing this theory, he avails himself of a licence in the use of the words idea and association, (although, in my opinion, with far greater ingenuity) strictly anologous to what we meet with in the works of Hartley.

Another coincidence, not less extraordinary, may be remarked between Hartley's Theory of the Mechanism of the Mind, and the speculations on the same subject, of the justly celebrated Charles Bonnet of Geneva.

In mentioning these historical facts, I have not the most distant intention of insinuating any suspicion of plagiarism; a suspicion which I never can entertain with respect to any writer of original genius, and of fair character, but upon the most direct and conclusive evidence. The two very respectable foreigners, whose names have been already mentioned in this note, have furnished another example of coincidence, fully as curious as either of the preceding: I allude to the hypothesis of the animated statue, which they both adopted about the same time, in tracing the origin and progress of our knowledge; and which neither seems to have borrowed, in the slightest degree, from any previous acquaintance with the speculations of the other.

* Hartley's Observations, pp. 511, 512.

matter, first occurred to my friend Mr. Mitchell, on reading "Baxter on the immateriality of the Soul.” He found that this author's idea of matter was, that it consisted, as it were, of bricks, cemented together by an immaterial mortar. These bricks, if he would be consistent to his own reasoning, were again composed of less bricks, cemented likewise by an immaterial mortar, and so on ad infinitum. This putting Mr. Mitchell upon the consideration of the several appearances of nature, he began to perceive, that the bricks were so covered with this immaterial mortar, that if they had any existence, at all, it could not possibly be perceived, every effect being produced, at least, in nine instances in ten certainly, and probably in the tenth also, by this immaterial, spiritual, and penetrable mortar. Instead, therefore, of placing the world upon the giant, the giant upon the tortoise, and the tortoise upon he could not tell what, he placed the world at once upon itself; and finding it still necessary, in order to solve the appearances of nature, to admit of extended and penetrable immaterial substance, if he maintained the impenetrability of matter, and observing farther, that all we perceive by contact, &c. is this penetrable immaterial substance, and not the impenetrable one, he began to think he might as well admit of penetrable material, as of penetrable immaterial substance, especially as we know nothing more of the nature of substance, than that it is something which supports properties, which properties may be whatever we please, provided they be not inconsistent with each other, that is, do not imply the absence of each other. This by no means seemed to be the case, in supposing two substances to be in the same place at the same time, without excluding each other; the objection to which is only derived from the resistance we meet with to the touch, and is a prejudice that has taken its rise from that circumstance, and is not unlike the prejudice against the antipodes, derived from the constant experience of bodies falling, as we account it, downwards." *

In the disquisitions on matter and spirit, by the same

* Pages 392, 393.