communication with it, except, as several of these philosophers suppose, through a fine, filmy, shadowy, unsubstantial medium, overlooking that it is the business of philosophy at all times to take facts as they are, to regard what is done; not to perplex itself with hypothetical impossibilities. What mind can do, and what matter can do, must be determined by dry facts. The best proof of the practicability of a thing is, that it takes place.

They might have known, by merely opening their eyes, that intelligent beings do see material objects, and that in this simple act they are utterly unconscious of any image, species, idea, representation, or whatever else a metaphysician might choose to call that imaginary entity.

Even philosophers who did not consider any independent entity of this kind to exist, held the kindred doctrine, that there is a purely mental phenomenon, which is the immediate thing perceived, either constituting the object itself, or intervening in some inexplicable way between the external object and the percipient being, so as practically to prevent him from getting at the object, or to keep it aloof from him; an hypothesis, in whatever way it may be put or expressed, that embodies as rank a fiction as the other.

It seems to have been only after a thousand struggles that the simple truth was arrived at, which is not by any means yet universally received

the truth that the perception of external things

through the organs of sense is a direct mental act or phenomenon of consciousness not susceptible of being resolved into anything else.

This notion that we do not perceive external objects themselves, but only the ideas of them, whether such ideas are to be regarded as modifications of consciousness, or as substantially distinct on the one hand from the percipient mind, and on the other from the external object, led philosophers into inevitable self-contradictions.

Locke, for example, in one part of his immortal Essay, is inconsistent enough to maintain that we perceive nothing but our own ideas, and yet that we have a knowledge of external objects, although he is evidently puzzled to explain how this can be. And well he might be puzzled. The doctrine which admits that we have a knowledge of external objects, yet at the same time maintains that we perceive only the ideas of such objects, not the objects themselves, is self-contradictory.

In order that we may be able to know what an idea is as a relative or representative phenomenon, we must know also what it relates to or represents, or, in other words, we must know also its correlative; just as to know what a son or a daughter is, we must know likewise what a parent is.

But if, according to the doctrine under review, we perceive only ideas, we are shut out from the possibility of knowing what the represented objects are; nay, even from the possibility of knowing that

such things as represented objects exist: no way is open by which the faintest suspicion of their existence could have access to us. We cannot, therefore, both know external objects, and yet perceive nothing but ideas. The two things are incompatible.

To escape from this contradiction, those who contend that we perceive only our own ideas, must admit that we have no knowledge of external objects: the term idea must be taken to denote something which is not relative or representative, something absolute or independent: it cannot signify a phenomenon or entity representing another phenomenon or entity called an external object. It becomes a positive term without reference to anything else, denoting the thing alone which is perceived: and thus all that the doctrine effects is the virtual re-introduction, under the name of ideas, of the things called external objects, ostensibly banished by it.

The whole is, in fact, however little it may be intended, a mere verbal quibble, stripping the word idea of its representative import, and then substituting it for external object, to which it thus becomes a bad, because an ambiguous, equivalent. Locke, who was doubtless the last man in the world intentionally to quibble*, braved the

In the opening of one of Mr. Stewart's Chapters, he is, however, plainly charged with this offence. The passage runs

inconsistency here pointed out, or rather was not adequately sensible of it. I have ventured to say that he puzzled himself on this particular matter, and I ought not to leave so heavy a charge against so distinguished a philosopher without the requisite proof; but as the evidence in support of it will occupy some space, I will reserve the subject for a separate letter.

as follows:-"Mr. Locke's quibbles founded on the word innate were early remarked by Lord Shaftesbury.”—Phil. Essays, p. 104.

LETTER XIV.

THEORIES OF PERCEPTION. - LOCKE.

LOCKE's perplexity on the point adverted to in my last letter is remarkable.

After telling us that the mind perceives nothing but its own ideas; that it knows not things immediately, but only by the intervention of the ideas it has of them; and yet that there are external things with which some of these ideas agree; he proceeds to say, that ideas are to be distinguished as they are in our minds, and as they are modifications of matter. But here is at once a difficulty.

For him to treat ideas as modifications of matter would obviously never do.

It appears to have immediately struck him that he could not consistently speak of ideas, as being in things themselves; he therefore requests when he so speaks, to be understood as meaning qualities in the objects (thus, by the way, virtually giving

* How necessary this request on his part was may be seen in such passages as the following: "That which produces any simple or complex idea we denote by the general name cause; and that which is produced, effect. Thus, finding that in that substance which we call wax, fluidity, which is a simple idea that was not in it before, is constantly produced by the application of a certain degree of heat, we call the simple idea