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 this phenomena of our dreams,—not that we actually saw and heard—thus evidently shewing, 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,—process both mental and corporeal,—so, I have no doubt, that idea, though now confined more strictly to the feelings 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 part 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 shew in my next Lecture.
Footnote
[92] On the Intellectual Powers, Essay II. c. 17.
[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, recognized by us as permanent and uniform in their nature; but are so recognized 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 forever 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.