to pretend to perfect divisions, but to leave room for fuch additions or alterations as a more perfect view of the fubject may afterwards fuggeft.

I fhall not, therefore, attempt a complete enumeration of the powers of the human understanding. I fhall only mention those which I propofe to explain, and they are the following:

1ft, The Powers we have by means of our external fenfes. 2dly, Memory. 3dly, Conception. 4thly, The Powers of refolving and analyfing complex objects, and compounding thofe that are more fimple. 5thly, Judging. 6thly, Reafoning. 7thly, Tafte. 8thly, Moral perception; and, last of all, Confcioufnefs.'

To each of the firft feven of the intellectual powers contained in the above enumeration, the Author has appropriated a diftinct eflay. He has alfo taken occafion to explain confcioufnefs, the laft of them, when giving an account of the first principles of contingent truths, in the effay concerning judgment. But he has not explained the faculty of moral perception in the prefent work, because, he fays, as it is an active as well as an intellectual power, and has an immediate relation to the other active powers of the mind, he apprehends that it is proper to defer the confideration of it till these be explained. We learn from this hint, which occurs at the end of the laft effay, that the Doctor proposes to publifh another treatife, in which he is to explain the powers of action in the human mind, and in which he will have occafion to explain the principles of morals. Though this important branch of knowledge has employed the abilities of feveral eminent writers during the prefent century, yet much light may ftill be expected from Dr. Reid's accurate judgment, and extenfive acquaintance with the powers of human nature.

Thofe effays which are prefented to the Public in this volume may be confidered as finished productions of long and laborious ftudy. They contain the substance of lectures which were delivered annually, firft in the univerfity of Aberdeen, and afterwards in that of Glafgow, for the fpace of thirty years, during which time they have been the objects of the Author's particular attention, and have, of confequence, undergone frequent and careful revifals. The reader, therefore, has no reason to expect any crude and random effufions of a brilliant fancy, nor any thing that has not undergone the fcrutiny of mature judg ment and reflection: and when, added to this, he takes into confideration the eminent abilities and difcernment of the Author, he may fee caufe for fufpending his decifion, though cafes fhould occur, in which he is inclined to differ from him in opiDion. The doctrines of many philofophers, whose names stand highest in this department of literature, are examined by the Author with freedom, and the foundation on which they are built is frequently attacked. But the weapon which he employs against them iş manly reasoning, free from that captious fophiftry which fo frequently difgraces metaphyfical writings, and not

3

polluted

polluted by the illiberality and petulance which fo frequently occur in the difcuffion of controverfial matters. He generally ftates opinions and arguments in the words of those who have published them, and though he deduces thofe confequences which he thinks fairly follow them, yet he does not impute to the authors of the premises any of the conclufions which they themselves have not drawn and avowed. Hence he candidly exempts from all fufpicion of scepticifm, feveral of those writers whofe principles feem to lead directly to that indecifive and comfortless fort of fpeculation.

The first of thefe effays is preliminary, and confifts of eight chapters. In imitation of the mathematicians, who have excluded wrangling and idle difputes from the fciences that refpect quantity and number, by defining accurately the terms which they have occafion to ufe, Dr. Reid devotes the first chapter of this effay to the explication of certain words, that frequently occur in the language of those philofophers who have treated of the human understanding. The terms which he has particularly explained, in this chapter, are mind, operations of mind, power and faculty, things in the mind and things external to the mind, thinking, perception, confciousness, conceiving, imagining and apprehending, object of perception, idea, impreffion, and fenfation. He obferves, that no proper logical dennition of fuch terms can be given; but the meaning of them may, however, be ascertained fo as to prevent all ambiguity and mistake in the application of them. He places in a very ftriking light the importance of fuch explications, by pointing out the manner in which fome of these words have been abufed by philofophical writers, perverted from their ufual meaning, and applied fometimes in one fignification and fometimes in another, with a view to prefent in a favourable light certain peculiar tenets. fhall infert, as a fpecimen, the explication of the terms perception and fenfation. We are the more difpofed to felect thefe, because inattention to the distinction between the operations of mind which they denote, appears to have been the principal occafion of certain paradoxical opinions, with regard to the existence both of matter and of fpirit, embraced by fome modern philofophers.

We

First, We are never faid to perceive things, of the existence of which we have not a full conviction. I may conceive or imagine a mountain of gold, or a winged horfe; but no man fays that he perceives fuch a creature of imagination. Thus perception is diftinguished from conception or imagination. Secondly, Perception is applied only to external objects, not to thofe that are in the mind itfelf. When I am pained, I do not fay that I perceive pain, but that I feel it, or that I am confcious of it. Thus perception is distinguished from confcioufnefs. Thirdly, The immediate object of perception must be fomething prefent, and not what is paft. We may remember what is paft, but do not perceive it. I may fay, I perceive fuch a perfon has

04

has had the fmall-pox; but this phrafe is figurative, although the figure is fo familiar that it is not obferved. The meaning of it is, that I perceive the pits in his face, which are certain figns of his having had the fmall-pox. We fay we perceive the thing fignified, when we only perceive the fign. But when the word perception is ufed properly, and without any figure, it is never applied to things paft. And thus it is diftinguished from remembrance.

In a word, perception is moft properly applied to the evidence we have of external objects by our fenfes. But as this is a very clear and cogent kind of evidence, the word is often applied by analogy to the evidence of reafon, or of teftimony, when it is clear and cogent. The perception of external objects by our fenfes, is an operation of the mind of a peculiar nature, and ought to have a name appropriated to it. It has fo in all languages. And, in English, I know no word more proper to exprefs this act of the mind than perception. Seeing, hearing, fmelling, tafting, and touching or feeling, are words that exprefs the operations proper to each fenfe; perceiving exprefles that which is common to them all.

The obfervations made on this word would have been unnecessary, if it had not been fo much abufed in philofophical writings upon the mind; for in other writings it has no obfcurity. Although this abufe is not chargeable on Mr. Hume only, yet I think he has carried it to the higheft pitch. The firft fentence of his treatife of human nature runs thus: "All the perceptions of the human mind refolve themselves into two diftin&t heads, which I fhall call impreffions and ideas." He adds, a little after, that under the name of impreffions, he comprehends all our fenfations, paffions, and emotions. Here we learn that our paffions and emotions are perceptions. I believe no English writer before him ever gave the name of a perception to any paflion or emotion. When a man is angry, we must fay that he has the perception of anger; when he is in love, that he has the perception of love. He fpeaks often of the perceptions of memory, and of the perceptions of imagination; and he might as well fpeak of the hearing of fight, or of the fmelling of touch: for, furely, hearing is not more different from fight, or fmelling from touch, than perceiving is from remembering or imagining.'

Senfation is a name given by philofophers to an act of mind, which may be diftinguished from all others by this, that it hath no object diftin&t from the act itfelf. Pain of every kind is an uneafy fenfation. When I am pained, I cannot fay that the pain I feel is one thing, and that my feeling it is another thing. They are one and the fame thing, and cannot be disjoined, even in imagination. Pain, when it is not felt, has no exiflenee. It can be neither greater nor lefs in degree or duration, nor any thing elfe in kind, than it is felt to be. It cannot exift by itself, nor in any fubject, but in a fentient being. No quality of an inanimate infentient being can have the leaft refemblance to it.

What we have faid of pain may be applied to every other fenfation. Some of them are agreeable, others uneafy, in various degrees. Thefe being objects of defire or averfion, have fome attention given to them; but many are indifferent, and fo little attended to, that they have no name in any language.

• Moft

• Moft operations of the mind, that have no names in common language, are complex in their nature, and made up of various ingredients, or more fimple acts; which, though conjoined in our con itution, must be disjoined by abstraction, in order to our having a diftinct and scientific notion of the complex operation. In fuch operations, fenfation for the most part makes an ingredient. Those who do not attend to the complex nature of fuch operations, are apt to refolve them into fome one of the fimple acts of which they are compounded, overlooking the others: and from this caufe many difputes have been raifed, and many errors have been occafioned with regard to the nature of fuch operations.

The perception of external objects is accompanied with fome fenfation correfponding to the object perceived, and fuch fenfations have, in many cafes, in all languages, the fame name with the external object which they always accompany. The difficulty of dif joining, by abftraction, things thus conftantly conjoined in the courfe of nature, and things which have one and the fame name in all languages, has likewife been frequently an occafion of errors in the philofophy of the mind. To avoid fuch errors, nothing is of more importance than to have a diftin&t notion of that fimple act of the mind which we call fenfation, and which we have endeavoured to describe. By this means we fhall find it more eafy to diftinguish it from every external object that it accompanies, and from every other act of the mind that may be conjoined with it. For this purpose, it is likewise of importance, that the name of fenfation fhould, in philofophical writings, be appropriated to fignify this fimple act of the mind, without including any thing more in its fignification, or being applied to other purposes."

I fhall add an obfervation concerning the word feeling. This word has two meanings. First, it fignifies the perceptions we have of external objects, by the fenfe of touch. When we speak of feeling a body to be hard or foft, rough or fmooth, hot or cold; to feel thefe things is to perceive them by touch. They are external things, and that act of the mind by which we feel them, is eafily diftinguished from the objects felt. Secondly, the word feeling is used to fignify the fame thing as fenfation, which we have just now explained; and, in this fenfe, it has no object; the feeling and the thing felt are, one

and the fame.

Perhaps betwixt feeling, taken in this laft fenfe, and fenfation," there may be this fmall difference, that fenfation is most commonly ufed to fignify thofe feelings which we have by our external fenfes and bodily appetites, and all our bodily pains and pleasures. But there are feelings of a nobler nature accompanying our affections, our moral judgments, our determinations in matters of taste, to which the word fenfation is lefs properly applied.'

In the fecond chapter of the preliminary essay, Dr. R. mené, tions certain principles which he takes for granted, as being felf-evident, and needing no proof. In this particular, as well as in the explication of his terms, he very judiciously follows the laudable practice of the mathematicians, which was intro-. duced into natural philofophy by Sir Ifaac Newton, and has

been productive of much benefit in that branch of science. He thinks, very juftly, that there is as much occafion for laying down first principles in the philofophy of mind as in other branches of human knowledge, becaufe fome ingenious men have fallen into inconclufive reafening from endeavouring to prove certain truths, which being felf-evident do not admit of proof. Defcartes thought it neceflary to prove his own exiltence; others have attempted to prove that thofe external things exift which are perceived by the fenfes. Sceptical writers found it no difficult task to overturn the arguments upon which these philofophers had founded their conclufions, and improving the advantage they had gained, as if the truths themselves had been fupported by no furer evidence than that which had been unneceffarily produced, denied that either the things perceived, or the percipient being, have any exiftence. Dr. Reid being no advocate for blind credulity, lays it down as a maxim, that we ought to be cautious that we do not adopt opinions as firft principles, which are not entitled to that character.' The only principles, accordingly, which he takes for granted, are selfevident truths, of the belief of which no man in his fenfes can seriously diveft himfelf, though fome of them have been doubted of, or denied, by a few fpeculative perfons in their studious hours.

It is natural for men, when things occur in the course of their inquiries which they do not fully comprehend, to indulge themfelves in forming gueffes and conjectures concerning them, and after contriving a plaufible theory, they are apt to substitute it in the place of knowledge, and to rely upon the fabric which has been erected by their own imaginations, as if it were a folid building. Men are alfo inclined to form opinions concerning matters which they have never examined, by fuppofing that they have a refemblance to other matters with which they are better acquainted. If we proceed in our refearches after truth in either of thefe ways, the probability is that we fhall be deceived. It is not likely that our conjectures will correfpond with the nature of things, or that the properties of things very different from one another are the fame. Many of those, however, who have treated of the mind have had recourfe to conjecture, with a view to explain facts, or have reafoned on the fuppofition that there is iomething in mind fimilar to body, fo that the powers and operations of the former may be explained and understood by means of an acquaintance with the latter. In oppofition to thefe unphilofophical modes of proceeding, Dr. Reid, in the two fubfequent chapters, treats, firft, of hypothefes, or conjectures, to which he thinks no regard whatever is due in the investigation of truth, and which ought of confequence to be banished from fcience; and, fecondly, of analogy, which, though ufeful in fome cafes,