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

From the very flight view of the subject, howev er, which has been already given, it is fufficiently evident, that this doctrine, which refers the origin of all our knowledge to the occafions furnished by fenfe, 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 fubjects of our own consciousness,) are not fuggefted to the mind immediately by the fenfations arifing from the ufe 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 firft occafions on which our various intellectual faculties are exercised, are furnished by the impreffions made on our organs of sense and confequently, that, without these impreffions, it would have been impoffible for us to arrive at the knowledge of our faculties. Agreeably to this explanation of the doctrine, it may undoubtedly be faid with plaufibility, (and, I am inclined to believe, with truth,) that the occafions on which all our notions are formed, are furnished either immediately or ultimately by fenfe; but, if I am not much miftaken, 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 fenfe, it does not lead to thofe confequences which have interested one party of philofophers in its defence, and another in its refutation.

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There is another very important confideration which deferves our attention in this argument: that,even on the fuppofition that certain impreffions on our organs of fenfe are neceffary to awaken the mind to a consciousness of its own existence, and to give rife 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 existence, of the material world. To facilitate the admiffion of this propofition, let us fuppofe a being formed in every other respect like man; but poffeffed of no fenfes, excepting those of hearing and fmelling. I make choice of these two fenfes, 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 poffibly have inferred from our occafional fenfations of fmell and found, would have been, that there exifted fome unknown caufe by which they were produced.

Let us fuppofe then a particular fenfation to be excited in the mind of fuch a being. The moment this happens, he muft neceffarily acquire the knowl edge of two facts at once: that of the existence of the fenfation; and that of his own existence, as a fentient 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 fenfations, he can compare them together in refpect of the pleafure or the pain they have afforded him; and will naturally defire the return of the agreeable fenfations, and be afraid of the return of those which were painful. If the fenfations of fmell and found are both excited in his mind at the same time, he can attend to either of them he chuses, 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 fenfations exifting in his mind, and conveying to him no information concerning matter, to exercise many of his moft important faculties; and amidst all thefe different modifications and operations of his mind, he would feel, with irresistible conviction, that they all belong to one and the fame

fentient and intelligent being; or, in other words, that they are all modifications and operations of himself. I fay nothing, at prefent, of the various fimple notions, (or fimple ideas, as they are commonly called,) which would arife in his mind; for example, the ideas of number, of duration, of cause and effect, of perfonal identity; all of which, though perfectly unlike his fenfations, could not fail to be fuggefted by means of them. Such a being, then, might know all that we know of mind at prefent; and as his language would be appropriated to mind folely, and not borrowed, by analogy, from material phenomena, he would even poffefs important advantages over us in conducting the ftudy of pneumatology.

From thefe obfervations it fufficiently appears, what is the real amount of the celebrated doctrine, which refers the origin of all our knowledge to our fenfations; and that, even granting it to be true, (which, for my own part, I am difpofed to do, in the fenfe 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 thofe notions which are commonly fuggefted to us, in the first inftance, by the perception of external objects, are neceffarily fubfequent 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 fuperfluous to thofe who recollect that, although it has, for many years paft, been a fubject of controverfy in England, it continues ftill to be implicitly adopted by the beft philofophical writers in France; and that it has been employed by some of them to support the fyftem of materialiẩm; and by others to fhew, that the intellectual diftinctions between man and brutes, arife entirely from the differences in their animal organization, and in their powers of external perception.

CHAPTER SECOND.

Of Attention.

WHEN we are deeply engaged in converfation, or occupied with any fpeculation that is interefting to the mind, the furrounding objects either do not produce in us the perceptions they are fitted to excite; or thefe perceptions are inftantly forgotten. A clock, for example, may strike in the fame room with us, without our being able, next moment, to recollect whether we heard it or not.

In these, and fimilar cafes, I believe, it is commonly taken for granted, that we really do not perceive the external object. From fome analogous facts, however, I am inclined to fufpect that this opinion is not well-founded. A perfon who falls asleep at church, and is fuddenly awaked, is unable to recollect the laft words spoken by the preacher; or even to recollect that he was fpeaking at all. And yet, that fleep does not fufpend entirely the powers of perception, may be inferred from this, that if the preacher were to make a fudden paufe in his dif course, every perfon in the congregation who was afleep would inftantly awake. In this cafe, therefore, it appears, that a perfon may be conscious of a perception, without being able afterwards to recollect it.

Many other inftances of the fame general fact might be produced. When we read a book, (efpecially in a language which is not perfectly familiar to us,) we muft perceive fucceffively every different letter, and muft afterwards combine thefe letters into fyllables and words, before we comprehend the meaning of a sentence. This process, however, pasfes through the mind, without leaving any trace in 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 fome cafes this judgment is founded on a variety of circumftances combined together; the conformation of the organ neceffary for diftinct vifion; the inclination of the optic axes; the diftinctness or indiftinctness of the minute parts of the object; the distances of the intervening objects from each other, and from the eye; and, perhaps, on other circumftances befides these and yet, in confequence of our familiarity with fuch procef. fes from our earlieft infancy, the perception feems to be instantaneous; and it requires much reafoning, to convince perfons unaccustomed to philofophical fpeculations, that the fact is otherwife.

Another inftance of a ftill more familiar nature, may be of use for the farther illuftration of the fame fubject. It is well known, that our thoughts do not fucceed each other at random, but according to certain laws of affociation, which modern philofophers 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 fubject to another, which, at first view, appears to be very remote from it; and that it requires a confiderable degree of reflection, to enable the perfon himself by whom the tranfition was made, to ascertain what were the intermediate ideas. A curious inftance of fuch a fudden transition is mentioned by Hobbes in his Leviathan. "In a company," (fays he,) " in which the converfation turn"ed on the civil war, what could be conceived more "impertinent, than for a person to ask abruptly, "What was the value of a Roman denarius? On a "little reflection, however, I was eafily able to trace "the train of thought which fuggefted the queftion: "for the original fubject of difcourfe naturally in

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