without leaving a trace behind them; while others become, as it were, a part of ourselves, and, by their accumulations, lay a foundation for our perpetual progrefs in knowledge. Without pretending to exhaust the subject, I fhall content myself at present with a partial folution of this difficulty, by illuftrating the dependence of memory upon two principles of our nature, with which it is plainly very intimately connected; attention, and the affociation of ideas.

I endeavored in a former chapter to fhew, that there is a certain act of the mind, (diftinguished, both by philofophers and the vulgar, by the name of attention,) without which even the objects of our perceptions make no impreffion on the memory. It is alfo matter of common remark, that the permanence of the impreffion which any thing leaves in the memory, is proportioned to the degree of attention which was originally given to it. The obfervation has been so often repeated, and is so manifeftly true, that it is unneceffary to offer any illuftration of it.*

I have only to observe farther, with refpect to attention, confidered in the relation in which it ftands to memory, that although it be a voluntary act, it requires experience to have it always under com

* It seems to be owing to this dependence of memory on attention, that it is easier to get by heart a composition, after a very few readings, with an attempt to repeat it at the end of each, than after a hundred readings without such an effort. The effort rouses the attention from that languid state in which it remains, while the mind is giving a passive reception to foreign ideas. The fact is remarked by lord Bacon, and is explained by him on the same principle to which I have referred it.

"Quæ expectantur et attentionem excitant, melius hærent quam quæ prætervolant. Itaque si scriptum aliquod vicies perlegeris, 66 non tam facile illud memoriter disces, quam si illud legas decies, "tentando interim illud recitare, et ubi deficit memoria, inspiciendo "librum."

BACON, Nov. Org. lib. ii. aph. 26.

mand. In the case of objects to which we have been taught to attend at an early period of life, or which are calculated to roufe the curiofity, or to affect any of our paffions, the attention fixes itfelf upon them, as it were spontaneoufly, and without any effort on our part, of which we are conscious How perfectly do we remember, and even retain, for a long courfe of years, the faces and the hand-writings of our acquaintances, although we never took any particular pains to fix them in the memory? On the other hand, if an object does not intereft some principle of our nature, we may examine it again and again, with a wish to treasure up the knowledge of it in the mind, without our being able to command that degree of attention which may lead us to recognize it the next time we see it. A perfon, for example, who has not been accustomed to attend particularly to horfes or to cattle, may study for a confiderable time the appearance of a horse or of a bullock, without being able a few days afterwards to pronounce on his identity; while a horse-dealer or a grazier recollects many hundreds of that clafs of animals with which he is converfant, as perfectly as he does the faces of his acquaintances. In order to account for this, I would remark, that although attention be a voluntary act, and although we are always able, when we choose, to make a momentary exertion of it; yet, unless the object to which it is derected be really interefting, in fome degree, to the curiofity, the train of our ideas goes on, and we immediately forget our purpose. When we are employed, therefore, in ftudying fuch an object, it is not an exclufive and fteady attention that we give to it, but we are lofing fight of it, and recurring to it every instant; and the painful efforts of which we are confcious, are not (as we are apt to fuppofe them to be) efforts of uncommon attention, but unfuccefsful attempts to keep the mind fteady to its object, and to exclude

the extraneous ideas, which are from time to time foliciting its notice.

If thefe obfervations be well founded, they afford an explanation of a fact which has been often remarked, that objects are easily remembered which affect any of the paffions.* The paffion affifts the memory, not in confequence of any immediate connection between them, but as it prefents, during the time it continues, a fteady and exclufive object to the attention.

The connection between memory and the affocia tion of ideas, is fo ftriking, that it has been fuppofed by fome, that the whole of its phenomena might be refolved into this principle. But this is evidently not the cafe. The affociation of ideas connects our various thoughts with each other, fo as to prefent them to the mind in a certain order; but it prefup poses the existence of thefe thoughts in the mind; or, in other words, it prefuppofes a faculty of retaining the knowledge which we acquire. It involves alfo a power of recognizing, as former objects of attention, the thoughts that from time to time occur to us; a power which is not implied in that law of our nature which is called the affociation of ideas. It is poffible, furely, that our thoughts might have fucceeded each other, according to the fame laws as at prefent, without fuggefting to us at all the idea of the past; and, in fact, this fuppofition is realised to a certain degree in the cafe of fome old men, who retain pretty exactly the information which they re. ceive, but are fometimes unable to recollect in what manner the particulars which they find connected

* "Si quas res in vita videmus parvas, usitatas, quotidianas, eas "meminisse non solemus; propterea quod nulla nisi nova aut ad"mirabili re commovetur animus. At si quid videmus aut audi"mus egregie turpe, aut honestum, inusitatum, magnum, incredi bile, ridiculum, id diu meminisse consuevimus."

Ad Herenn. lib. 3.

together in their thoughts, at first came into the mind; whether they occurred to them in a dream, or were communicated to them in converfation.

On the other hand, it is evedent, that without the affociating principle, the powers of retaining our thoughts, and of recognizing them when they ocur to us, would have been of little ufe; for the most important articles of our knowledge might have remained latent in the mind, even when thofe occafions prefented themselves to which they are immediately applicable. In confequence of this law of our nature, not only are all our various ideas made to pass, from time to time, in review before us, and to offer themselves to our choice as fubjects of meditation, but when an occafion occurs which calls for the aid of our paft experience, the occafion itself recals to us all the information upon the fubject which that experience has accumulated.

The foregoing obfervations comprehend an analyfis of memory fufficiently accurate for my prefent purpose fome other remarks, tending to illuftrate the fame fubject more completely, will occur in the remaining fections of this chapter.

It is hardly neceffary for me to add, that when we have proceeded fo far in our inquiries concerning Memory, as to obtain an analysis of that power, and to afcertain the relation in which it ftands to the other principles of our conftitution, we have advanced as far towards an explanation of it as the nature of the fubject permits. The various theories which have attempted to account for it by traces or impreffions in the fenforium, are obviously too unphilofophical to deserve a particular refutation.* Such, indeed, is the poverty of language, that we cannot speak on the subject without employing expreffions

* See Note [S.]

which fuggeft one theory or another; but it is of importance for us always to recollect, that these expreffions are entirely figurative, and afford no explanation of the phenomena to which they refer. It is partly with a view to remind my readers of this confideration, that, finding it impoffible to lay afide completely metaphorical or analogical words, I have ftudied to avoid fuch an uniformity in the employment of them, as might indicate a preference to one theory rather than another; and by doing so, have perhaps fometimes been led to vary the metaphor oftener and more fuddenly, than would be proper in a compofition which aimed at any degree of elegance. This caution in the use of the common language concerning memory, it seemed to me the more neceffary to attend to, that the general dispofition which every perfon feels at the commencement of his philofophical pursuits, to explain the phenomena of thought by the laws of matter, is, in the cafe of this particular faculty, encouraged by a variety of peculiar circumftances. The analogy between committing a thing to memory that we with to remember, and engraving on a tablet a fact that we wish to record, is fo ftriking as to prefent itself even to the vulgar; nor is it perhaps lefs natural to indulge the fancy in confidering memory as a fort of repofitory, in which we arrange and preserve for future use the materials of our information. The immediate dependence, too, of this faculty on the ftate of the body, which is more remarkable than that of any other faculty whatever, (as appears from the effects produced on it by old age, difeafe, and intoxication,) is apt to ftrike thofe who have not been much converfant with thefe inquiries, as beftowing fome plaufibility on the theory which attempts to explain its phenomena on mechanical principles.

I cannot help taking this opportunity of expreff ing a wifh, that medical writers would be at