of the consciousness of the mind, which is a different substance. It is sufficient for us to believe, that there are external causes of this feeling of the mind, permanent and independent of it, which produce in regular series, all those phenomena that are found by us in the physical events of the universe, and with the continuance of which, therefore, our perceptions also will continue; we cannot truly suppose more, without conceiving our very notion of extension, a mental state, to be itself a body extended, which we have as little reason to suppose, as that our sensation of fragrance, another mental state, is itself a fragrant body. It is needless to prolong this discussion, by endeavouring to place the argument in new points of view. The simple answer to the question, "Is our notion of extension, or of the other primary - qualities of matter, a phenomenon or affection of matter or of mind ?" would be of itself sufficient; for if it be a state of the mind, as much as our feeling of heat or of fragrance, and a state produced by the presence of an external cause, as our sensations of heat or fragrance are produced, then there is no reason to suppose, that the knowledge is, in one case, more direct than in the other. In both, it is the effect of the presence of an external cause, and in both it must be relative only-to adopt Dr. Reid's phrase,-to that particular cause which produced it; the knowledge of which cause, in the case of extension, as much as in the case of fragrance, is nothing more than the knowledge, that there is without us, something which is not our mind itself, but which exists, as we cannot but believe, permanently and independently of our mind, and produces according to its own varieties, in relation to our corporeal frame at one time, that affection of the mind which we denominate the perception of extension; at another time, that different affection of the mind, which we denominate the perception of fragrance. What it is, as it exists in absolute independence of our perceptions, we who become acquainted with it, only by those very perceptions, know not, in either case; but we know it at least,-which is the only knowledge important for us,as it exists relatively to us; that is to say, it is impossible for us, from the very constitution of our nature, not to regard the variety of our perceptions, as occasioned by a corresponding variety of causes, external to our mind; though, even in making this reference, we must still believe our perceptions themselves, to be altogether different and distinct from the external causes, whatever they may be, which have produced them; to be, in short, phenomena purely mental, and to be this equally, whether they relate to the primary or the secondary qualities of matter; our notion of extension, in whatever way the Deity may have connected it with the presence of external things, being as much a state of the mind itself, as our notion of sweetness or sound.

These observations, on the process of suggestion, which, in the reference to an external cause, distinguishes our perceptions from our simpler sensations, and on the real and supposed differences of the primary and secondary qualities of matter,—will have prepared you, I trust, for understanding better the claim which Dr. Reid has made to the honour of overthrowing what he has termed the ideal system of perception. It is a claim, as I have said, which appears to me truly wonderful, both as made by him and admitted by others; the mighty achievement which appeared to him to be the overthrow of a great system, being nothing more, than the proof that certain phrases are metaphorical, which were intended by their authors to be understood only as metaphors.

In perception there is, as I have already frequently repeated, a certain

series, the presence of an external object-the affection of the sensorial organ-the affection of the sentient mind. As the two last, however, belong to one being-the being called self-which continues the same, while the external objects around are incessantly changing;-it is not wonderful, that, in speaking of perception, we should often think merely of the object as one, and of ourself, (this compound of mind and matter,) as also one,--uniting the organic and mental changes, in the single word which expresses our perception. To see and to hear, for example, are single words, expressive of this whole process-the bodily as well as the mental part-for we do not consider the terms as applicable, in strict philosophic propriety, to cases, in which the mere mental affection is the same, but the corporeal part is believed by us to be different,—as in sleep, or reverie, when the castle, the forest, the stream, rise before us as in reality, and we feel as if we were truly listening to voices which we love. That we feel, as if we were listening, and feel as if we saw, is our language, when, in our waking hours, we speak of these phenomena of our dreams, not that we actually saw and heard thus evidently showing, that we comprehend, in these terms,-when used without the qualifying words as if not the mental changes of state only, but the whole process of perception, corporeal as well as mental. The mere organic part of the process, however, being of importance, only as it is followed by the mental part, and being always followed by the mental part,— scarcely enters into our conception, unless in cases of this sort, when we distinguish perception from vivid imagination, or when the whole compound process of perception is a subject of our philosophic inquiry. As sight, hearing, perception, involve, in a single word,—a process both mental and corporeal, so, I have no doubt, the word idea, though now confined more strictly to the feeling of the mind, was long employed with a more vague signification, so as sometimes to mean the mental affection, sometimes the organic affection, sometimes both;-in the same manner, as at present we speak of sight, sometimes as mental, sometimes as organic, sometimes as both. It comprehends both, when we distinguish the mountain or forest which we see, from the mountain or forest of which we dream. It is mental only, when we speak of the pleasure of sight. It is organic only, when we say of an eye, in which the passage of the rays of light has become obstructed, that its sight is lost, or has been injured by disease.

The consideration of this double sense of the term idea, in some of the older metaphysical writers, corresponding with our present double sense of the word perception, as involving both the corporeal and mental parts of the process, removes, I think, much of that apparent confusion, which is sometimes to be found in their language on the subject; when they combine with the term expressions, which can be understood only in a material sense, after combining with it, at other times, expressions, which can be understood only of the mind; as it is not impossible that a period may arrive, when much of our reasoning, that involves no obscurity at present, may seem obscure and confused to our successors, in that career of inquiry, which, perhaps, is yet scarcely begun; merely because they may have limited with stricter propriety, to one part of a process, terms, which we now use as significant of a whole process. In the same manner, as we now exclude wholly from the term idea every thing organic, so may every thing organic hereafter be excluded from the term sight; and from the simple phrase, so familiar at present, that an eye has lost its sight, some future philosopher may be inclined to

assert, that we who now use that phrase, consider the perception of vision, as in the material organ; and if he have the talents of Dr. Reid, he may even form a series of admirable ratiocinations, in disproof of an opinion which nobody holds, and may consider himself, and perhaps too, if he be as fortunate as the author of the Inquiry into the Human Mind, may be considered, by others, as the overthrower of a mighty system of metaphysical illusion.

How truly this has been the case, in the supposed overthrow of the ideal system, I shall proceed to show in my next Lecture.

LECTURE XXVI.

ON DR. REID'S SUPPOSED CONFUTATION OF THE IDEAL SYSTEM; HYPOTHESIS OF THE PERIPATETICS REGARDING PERCEPTION; AND OPINIONS OF VARIOUS PHILOSOPHERS ON THE SAME SUBJECT.

THE remarks which I offered, in my last Lecture, in illustration of what have been termed the primary and secondary qualities of matter, were intended chiefly to obviate that false view of them, in which the one set of these qualities is distinguished, as affording us a knowledge that is direct, and the other set, a knowledge that is relative only;—as if any qualities of matter could become known to the mind, but as they are capable of affecting the mind with certain feelings, and as relative, therefore, to the feelings which they excite. What matter is, but as the cause of those various states of mind, which we denominate our sensations or perceptions, it is surely impossible for us, by perception, to discover. The physical universe, amid which we are placed, may have innumerable qualities that have no relation to our percipient mind, and qualities, which, if our mind were endowed with other capacities of sensation, we might discover as readily as those which we know at present; but the qualities that have no relation to the present state of the mind, cannot to the mind, in its present state, be elements of its knowledge. From the very constitution of our nature, indeed, it is impossible for us not to believe, that our sensations have external causes, which correspond with them, and which have a permanence, that is independent of our transient feelings,-a permanence, that enables us to predict in certain circumstances the feelings which they are again to excite in our percipient mind; and to the union of all these permanent external causes, in one great system, we give the name of the material world. But the material world, in the sense in which alone we are entitled to speak of it, is still only a name for a multitude of external causes of our feelings, of causes which are recognised by us as permanent and uniform in their nature; but are so recognised by us, only because, in similar circumstances, they excite uniformly in the mind the same perceptions, or, at least, are supposed by us to be uniform in their own nature, when the perceptions which they excite in us are uniform. It is according to their mode of affecting the mind, then, with various sensations, that we know them,—and not according to their own absolute nature, which it is impossible for us to know,-whether we give the

name of primary or secondary to the qualities which affect us. If our sensations were different, our perceptions of the qualities of things, which induce these sensations in us, would instantly have a corresponding difference. All the external existences which we term matter, and all the phenomena of their motion or their rest,-if known to us at all, are known to us only by exciting in us, the percipients of them, certain feelings and qualities, which are not more or less directly relative to our feelings, as sentient or percipient beings, are, therefore, qualities which we must be for ever incapable even of divining.

This, and some other discussions which have of late engaged us, were in part intended as preparatory to the inquiry on which we entered in the close of my Lecture, the inquiry into the justness of the praise which has been claimed and received by Dr. Reid, as the confuter of a very absurd theory of perception, till then universally prevalent :—and if, indeed, the theory, which he is said to have confuted, had been the general belief of philosophers till confuted by him, there can be no question, that he would have had a just claim to be considered as one of the chief benefactors of the Philosophy of Mind. At any rate, since this glory has been ascribed to him, and his supposed confutation of the theory of perception, by little images of objects conveyed to the mind, has been considered as forming one of the most important eras in intellectual science, it has acquired, from this universality of mistake with respect to it, an interest which, from its own merits, it would certainly be far from possessing.

In the Philosophy of the Peripatetics, and in all the dark ages of the scholastic followers of that system, ideas were truly considered as little images derived from objects without; and, as the word idea still continued to be used after this original meaning had been abandoned, (as it continues still, in all the works that treat of perception,) it is not wonderful that many of the accustomed forms of expression, which were retained together with it should have been of a kind that, in their strict etymological meaning, might have seemed to harmonize more with the theory of ideas as images, which prevailed when these particular forms of expression originally became habitual, than with that of ideas as mere states of the mind itself; since this is only what has happened with respect to innumerable other words, in the transmutations of meaning which they have received during the long progress of scientific inquiry. The idea, in the old philosophy, had been that, of which the presence immediately preceded the mental perception,the direct external cause of perception; and accordingly, it may well be supposed, that when the direct cause of perception was believed to be, not a foreign phantasm, but a peculiar affection of the sensorial organ, that word, which had formerly been applied to the supposed object, would still imply some reference to the organic state, which was believed to supply the place of the shadowy film, or phantasm, in being, what it had been supposed to be, the immediate antecedent of perception. Idea, in short, in the old writers, like the synonymous word perception at present, was expressive, not of one part of a process, but of two parts of it. It included with a certain vague comprehensiveness, the organic change as well as the mental,—in the same way as perception now implies a certain change produced in our organs of sense, and a consequent change in the state of the mind; and hence it is surely not very astonishing, that while many expressions are found in the works of these older writers, which, in treating of ideas, have a reference to 33

VOL. I.

the mental part of the process of perception, other expressions are occasionally employed which relate only to the material part of the process,—since both parts of the process, as I have said, were, to a certain degree, denoted by that single word. All this might very naturally take place, though nothing more was meant to be expressed by it than these two parts of the process,the organic change, whatever it might be, and the subsequent mental change, without the necessary intervention of something distinct from both, such as Dr. Reid supposes to have been meant by the term Idea.

It is this application, to the bodily part of the process, of expressions, which he considered as intended to be applied to the mental part of perception, that has sometimes misled him in the views which he has given of the opinions of former philosophers. But still more frequently has he been misled, by understanding in a literal sense phrases which were intended in a metaphorical sense, and which seem so obviously metaphorical, that it is truly difficult to account for the misapprehension. Indeed, the same metaphors, on the mere use of which Dr. Reid founds so much, continue still to be used in the same manner as before he wrote. We speak of impressions on the mind, of ideas bright or obscure, permanent or fading,-of senses, that are the inlets to our knowledge of external things,-and of memory, in which this knowledge is stored,-precisely as the writers and speakers before us used these phrases; without meaning any thing more, than that certain organic changes, necessary to perception, are produced by external objects,— and that certain feelings, similar to those originally excited in this manner, are afterwards renewed, with more or less permanence and vivacity, without the recurrence of the objects that originally produced them ;-and to arrange all the moods and figures of logic in confutation of mere metaphors, such as I cannot but think the images in the mind to have been, which Dr. Reid so powerfully assailed, seems an undertaking not very different from that of exposing, syllogistically and seriously, all the follies of Grecian Paganism, as a system of theological belief, in the hope of converting some unfortunate poetaster or poet, who still talks, in his rhymings to his mistress, of Cupid and the Graces.

There is, however, one very important practical inference to be drawn from this misapprehension,-the necessity of avoiding, as much as possible, in philosophic disquisition, the language of metaphor, especially when the precise meaning has not before been pointed out, so as to render any misconception of the intended meaning, when a metaphor is used, as nearly impossible as the condition of our intellectual nature will allow. In calculating the possibility of this future misconception, we should never estimate our own perspicuity very highly; for there is always in man a redundant facility of mistake, beyond our most liberal allowance. As Pope truly says,—

"The difference is as great between

The optics seeing, as the objects seen ;"

and, unfortunately, it is the object only which is in our power. The fallible optics, that are to view it, are beyond our control; and whatever opinion, therefore, the most cautious philosopher may assert, he ought never to flatter himself with the absolute certainty, that, in the course of a few years, he may not be exhibited, and confuted, as the assertor of a doctrine, not merely different from that which he has professed, but exactly opposite to it.