much mistaken, this is not the meaning which is com. monly 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. 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 smelling. 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 smell and found, would have been, that there existed some 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 must neceffarily acquire the knowledge of two facts at once: that of the existence of the fen fation; and that of his own existence, as a fentient being. After the fenfation 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 fame time, he can attend to either of them he chufes, and withdraw his attention from the other; or he can withdraw his attention from both, and fix it on fome fenfation he has felt formerly. In this manner, he might be led, merely by fenfations existing in his mind, and conveying to him no information concerning matter, to exercise many of his most important faculties; and amidst all thefe different modifications and operations of his mind, he would feel, with irrefiftible 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 himfelf.-I fay nothing, at present, 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 caufe and effect, of perfonal identity; all of which, though perfectly unlike his fenfations, could not fail to be fuggested 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 H 3 poffefs poffefs important advantages over us in conducting the study 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 firft 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 those who recollect that, although it has, for many years past, been a fubject of controverfy in England, it continues ftill to be implicitly adopted by the best philofophical writers in France; and that it has been employed by fome of them to support the fyftem of materialism; and by others to fhew, that the intellectual diftinctions between man and brutes, arife entirely from the differ ences 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 these perceptions are inftantly forgotten. A clock, for example, may ftrike 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 afleep at church, and is suddenly awaked, is unable to recollect the last 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 percep tion, may be inferred from this, that if the preacher were to make a fudden pause in his discourse, every perfon in the congregation who was afleep, would instantly awake. In this cafe, therefore, it appears, that a person 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, (especially in H 4 a lan a language which is not perfectly familiar to us,) we must perceive fucceffively every different letter, and muft afterwards combine thefe letters into fyllables and words, before we comprehend the meaning of a fentence. This procefs, however, paffes through the mind, without leaving any trace in the memory. It has been proved by optical writers, that, in perceiving the distances of vifible 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 diftin&t vifion; the inclination of the optic axes; the diftin&tness 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 circumstances befides these and yet, in confequence of our familiarity with fuch proceffes from our earliest infancy, the perception feems to be inftantaneous; and it requires much reafoning, to convince perfons unac. customed to philofophical fpeculations, that the fact is otherwise. Another inftance of a ftill more familiar nature, may be of ufe 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 cer tain 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 fudden tranfition from one subject to another, which, at first view, appears to be very remote from it; and that it requires |