influence, which the will poffeffes over the members of the body; and to thofe powers of perception, which feem to inform us, by a fort of infpiration, of the various changes which take place in the external univerfe. Of those who receive the advantages of a liberal education, there are perhaps few, who pafs the period of childhood, without feeling their curiofity excited by this incomprehenfible communication between mind and matter. For my own part, at least, I cannot recollect the date of my earlieft fpeculations on the fubject.

It is to the phenomena of perception alone, that I am to confine myfelf in the following effay; and even with respect to thefe, all that I propofe, is to offer a few general remarks on fuch of the common mistakes concerning them, as may be most likely to Iniflead us in our future inquiries. Such of my readers as wish to confider them more in detail, will find ample fatisfaction in the writings of Dr. Reid.

In confidering the phenomena of perception, it is natural to fuppofe, that the attention of philofophers would be directed, in the first inftance, to the sense of feeing. The variety of information and of enjoyment we receive by it; the rapidity with which this information and enjoyment are conveyed to us; and above all, the intercourse it enables us to maintain with the more diftant part of the universe, cannot fail to give it, even in the apprehenfion of the most careless obferver, a pre-eminence over all our other perceptive faculties. Hence it is, that the various theories, which have been formed to explain the operations of our fenfes, have a more immediate reference to that of feeing; and that the greater part of the metaphyfical language, concerning perception in general, appears evidently, from its etymology, to have been fuggefted by the phenomena of vifion. Even when applied to this fenfe, indeed, it can at moft amuse the fancy, without conveying any pre

cife knowledge; but, when applied to the other fenfes, it is altogether abfurd and unintelligible.

It would be tedious and uteless, to confider particularly, the different hypothefis which have been advanced upon this fubject. To all of them, I apprehend, the two following remarks will be found applicable: First, that, in the formation of them, their authors have been influenced by fome general maxims of philofophifing, borrowed from phyfics; and, fecondly, that they have been influenced by an indiftinct, but deep-rooted, conviction, of the immateriality of the foul; which, although not precife enough to point out to them the abfurdity of attempting to illuftrate its operations by the analogy of matter, was yet fufficiently strong, to induce them to keep the abfurdity of their theories as far as poffible out of view, by allufions to thofe phyfical facts, in which the diftinctive properties of matter are the leaft grossly and palpably exposed to our obfervation. To the former of thefe circumftances, is to be afcribed, the general principle, upon which all the known theories of perception proceed; that, in order to explain the intercourfe between the mind and diftant objects, it is neceffary to fuppofe the existence of fomething intermediate, by which its perceptions are produced; to the latter, the various metaphorical expreffions of ideas, fpecies, forms, fhadows, phan tafms, images; which, while they amufed the fancy with fome remote analogies to the objects of our fenfes, did not directly revolt our reafon, by prefenting to us any of the tangible qualities of body.

"It was the doctrine of Aristotle, (fays Dr. Reid) "that, as our fenfes connot receive external materi"al objects themselves, they receive their species; "that is, their images or forms, without the mat"ter; as wax receives the form of the feal, "without any of the matter of it. Thefe images "or forms, impreffed upon the fenfes, are called fen

"fible fpecies; and are the objects only of the fenfi"tive part of the mind: but by various, internal "powers, they are retained, refined, and fpirituali"zed, fo as to become objects of memory and ima"gination; and at last, of pure intellection. When "they are objects of memory and imagination, they ઃઃ get the name of phantafms. When, by farther re"finement, and being ftripped of their particulari"ties, they become objects of science, they are cal"led intelligible fpecies: fo that every immediate object, whether of fenfe, of memory, of imagination, "or of reafoning, muft be fome phantafm, or fpe"cies, in the mind itself.

"The followers of Ariftotle, especially the fchoolEC men, made great additions to this theory; which "the author himself mentions very briefly, and with "an appearance of referve. They entered into large "difquifitions with regard to the fenfible fpecies, "what kind of things they are; how they are fent "forth by the object, and enter by the organs of the "fenfes; how they are preferved, and refined by va"rious agents, called internal fenfes, concerning the "number and offices of which they had many con"troverfies."*

The Platonists, too, although they denied the great doctrine of the Peripatetics, that all the objects of human understanding enter at firft by the fenfes ; and maintained, that there exift eternal and immutable ideas, which were prior to the objects of sense, and about which all fcience was employed; yet appear to have agreed with them in their notions concerning the mode in which external objects are perceived. This, Dr. Reid infers, partly from the fi lence of Ariftotle about any difference between himfelf and his mafter upon this point; and partly from a paffage in the feventh book of Plato's Republic; in which he compares the procefs of the mind in perEssays on the Intellectual Powers of Man, p. 25.

ception, to that of a perfon in a cave, who fees not external objects themselves, but only their shadows.*

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"Two thousand years after Plato, (continues Dr. "Reid,) Mr. Locke, who ftudied the operations of "the human mind fo much, and with fo great fuc"cefs, reprefents our manner of perceiving external objects, by a fimilitude very much refembling that "of a cave." Methinks," fays he, "the under❝ftanding is not much unlike a closet, wholly shut "from light, with only fome little opening left, to "let in external vifible refemblances or ideas of "things without. Would the pictures coming into "fuch a dark room but ftay there, and lie fo orderly "as to be found upon occafion, it would very much "refemble the understanding of a man, in reference "to all objects of fight, and the ideas of them."t

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"Plato's fubterranean cave, and Mr Locke's dark 66 closet, may be applied with eafe to all the systems "of perception, that have been invented: for they "all fuppofe, that we perceive not external objects "immediately; and that the immediate objects of "perception, are only certain fhadows of the exter"nal objects. Those fhadows, or images, which we "immediately perceive, were by the ancients called Species, forms, phantafms. Since the time of Des "Cartes, they have commonly been called ideas; t "and by Mr. Hume, impreffions. But all the philof. "ophers, from Plato to Mr. Hume, agree in this, "that we do not perceive external objects immedi66 ately; and that the immediate object of percep"tion must be fome image prefent to the mind." On the whole, Dr. Reid remarks, "that in their fentiments concerning perception, there appears "an uniformity, which rarely occurs upon fubjects of fo abftrufe a nature."§

* Ibid. p. 99.

† Locke on Human Understanding, book ii. chap. 11. § 17. Reid, p. 116, 117.

+ See Note [B.]

The very fhort and imperfect review we have now taken, of the common theories of perception, is almoft fufficient, without any commentary, to ef*tablish the truth of the two general obfervations formerly made; for they all evidently proceed on a fuppofition, fuggefted by the phenomena of phyfics, that there must of neceffity exift fome medium of communication between the objects of perception and the percipient mind; and they all indicate a fecret conviction in their authors, of the effential diftinction between mind and matter; which, although not rendered, by reflection, sufficiently precife and fatisfactory, to fhew them the abfurdity of attempting to explain the mode of their communication; had yet fuch a degree of influence on their fpeculations, as to induce them to exhibit their fuppofed medium under as myfterious and ambiguous a form as poffible, in order that it might remain doubtful, to which of the two predicaments, of body or mind, they meant that it fhould be referred. By refining away the groffer qualities of matter; and by allufions to fome of the most aerial and magical appear ances it affumes, they endeavored, as it were, to fpiritualize the nature of their medium; while, at the fame time, all their language concerning it, implied fuch a reference to matter, as was neceflary for furnishing a plausible foundation, for applying to it the received maxims of natural philofophy.

Another obfervation, too, which was formerly hinted at, is confirmed by the fame hiftorical review; that, in the order of inquiry, the phenomena of vifion had firft engaged the attention of philofophers; and had fuggefted to them the greater part of their language, with respect to perception in general; and that in confequence of this circumstance, the common modes of expreflion on the subject, unphilofophical and fanciful at beft, even when applied to the sense of seeing,are,in the cafe of all the other