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the material world, and to exert all the different modifications of thought of which it is capable.

From the very slight view of the subject, however, which has been already given, it is sufficiently evident, that this doctrine, which refers the origin of all our knowledge to the occasions furnished by sense, must be received with many limitations. That those ideas, which Mr. Locke calls ideas of reflection, (or, in other words, the notions which we form of the subjects of our own consciousness,) are not suggested to the mind immediately by the sensations arising from the use of our organs of perception, is granted on all hands: and, therefore, the amount of the doctrine now mentioned, is nothing more than this; that the first occasions on which our various intellectual faculties are exercised, are furnished by the impressions made on our organs of sense, and consequently, that, without these impressions, it would have been impossible for us to arrive at the knowledge of our faculties. Agreeably to this explanation of the doctrine, it may undoubtedly be said with plausibility, (and, I am inclined to believe, with truth,) that the occasions on which all our notions are formed, are furnished either immediately or ultimately by sense; but, if I am not much mistaken, this is not the meaning which is commonly annexed to the doctrine, either by its advocates or their opponents. One thing at least is obvious, that, in this sense, it does not lead to those consequences which have interested one party of philosophers in its defence, and another in its refutation.

There is another very important consideration which deserves our attention in this argument: that, even on the supposition that certain impressions on our organs of sense are necessary to awaken the mind to a consciousness of its own existence, and to give rise to the exercise of its various faculties, yet all this might have happened, without our having any knowledge of the qualities, or even of the ex

istence, of the material world. To facilitate the admission of this proposition, let us suppose a being formed in every other respect like man, but possessed of no senses, excepting those of hearing and smelling. I make choice of these two senses, because it is obvious, that by means of them alone we never could have arrived at the knowledge of the primary qualities of matter, or even of the existence of things external. All that we could possibly have inferred from our occasional sensations of smell and sound, would have been, that there existed some unknown cause by which they were produced.

Let us suppose then a particular sensation to be excited in the mind of such a being. The moment this happens, he must necessarily acquire the knowledge of two facts at once that of the existence of the sensation, and that of his own existence, as a sentient being. After the sensation is at an end, he can remember he felt it; he can conceive that he feels it again. If he has felt a variety of different sensations, he can compare them together in respect of the pleasure or the pain they have afforded him, and will naturally desire the return of the agreeable sensations, and be afraid of the return of those which were painful. If the sensations of smell and sound are both excited in his mind at the same time, he can attend to either of them he chooses, and withdraw his attention from the other, or he can withdraw his attention from both, and fix it on some sensation he has felt formerly. In this manner, he might be led, merely by sensations existing in his mind, and conveying to him no information concerning matter, to exercise many of his most important faculties; and amidst all these different modifications and operations of his mind, he would feel, with irresistible conviction, that they all belong to one and the same sentient and intelligent being, or, in other words, that they are all modifications and operations of himself.—I say nothing, at present, of the various

simple notions, (or simple ideas, as they are commonly called,) which would arise in his mind; for example, the ideas of number, of duration, of cause and effect, of personal identity; all of which, though perfectly unlike his sensations, could not fail to be suggested by means of them. Such a being, then, might know all that we know of mind at present, and as his language would be appropriated to mind solely, and not borrowed by analogy from material phenomena, he would even possess important advantages over us in conducting the study of pneumatology.

From these observations it sufficiently appears, what is the real amount of the celebrated doctrine, which refers the origin of all our knowledge to our sensations; and that, even granting it to be true, (which, for my own part, I am disposed to do, in the sense in which I have now explained it,) it would by no means follow from it, that our notions of the operations of mind, nor even many of those notions which are commonly suggested to us, in the first instance, by the perception of external objects, are necessarily subsequent to our knowledge of the qualities, or even of the existence, of matter.

The remarks which I have offered on this doctrine will not appear superfluous to those who recollect that, although it has, for many years past, been a subject of controversy in England, it continues still to be implicitly adopted by the best philosophical writers in France; and that it has been employed by some of them to support the system of materialism, and by others to shew, that the intellectual distinctions between man and brutes arise entirely from the differences in their animal organization, and in their powers of external perception.

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CHAPTER SECOND.

OF ATTENTION.

WHEN we are deeply engaged in conversation, or occupied with any speculation that is interesting to the mind, the surrounding objects either do not produce in us the perceptions they are fitted to excite, or these perceptions are instantly forgotten. A clock, for example, may strike in the same room with us, without our being able, next moment, to recollect whether we heard it or not.

In these, and similar cases, I believe, it is commonly taken for granted, that we really do not perceive the external object. From some analogous facts, however, I am inclined to suspect that this opinion is not well founded. A person who falls asleep at church, and is suddenly awaked, is unable to recollect the last words spoken by the preacher; or even to recollect that he was speaking at all. And yet, that sleep does not suspend entirely the powers of perception, may be inferred from this, that if the preacher were to make a sudden pause in his discourse, every person in the congregation, who was asleep, would instantly awake. In this case, therefore, it appears, that a person may be conscious of a perception, without being able afterwards to recollect it.

Many other instances of the same general fact might be produced. When we read a book, (especially in a language which is not perfectly familiar to us,) we must perceive successively every different letter, and must afterwards combine these letters into syllables and words, before we comprehend the meaning of a sentence. This

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process, however, passes through the mind, without leaving any trace on the memory.

It has been proved by optical writers, that, in perceiving the distances of visible objects from the eye, there is a judgment of the understanding antecedent to the perception. In some cases this judgment is founded on a variety of circumstances combined together; the conformation of the organ necessary for distinct vision; the inclination of the optic axes; the distinctness or indistinctness of the minute parts of the object; the distances of the intervening objects from each other, and from the eye; and, perhaps, on other circumstances besides these and yet, in conse-、 quence of our familiarity with such processes from our earliest infancy, the perception seems to be instantaneous ; and it requires much reasoning,, to convince persons unaccustomed to philosophical speculations, that the fact is otherwise.

Another instance of a still more familiar nature, may be of use for the farther illustration of the same subject. It is well known, that our thoughts do not succeed each other at random, but according to certain laws of association, which modern philosophers have been at much pains to investigate. It frequently, however, happens, particularly when the mind is animated by conversation, that it makes a sudden transition from one subject to another, which, at first view, appears to be very remote from it; and that it requires a considerable degree of reflection, to enable the person himself by whom the transition was made, to ascertain what were the intermediate ideas. A curious instance of such a sudden transition is mentioned by Hobbes in his Leviathan. "In a company," (says he,) "in which the conversation turned on the civil war, what "could be conceived more impertinent, than for a person "to ask abruptly, What was the value of a Roman dena"rius? On a little reflection, however, I was easily able

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