sciences have a relation to human nature; and, however wide any of them may seem to run from it, they still return back by one passage or another. This is the centre and capital of the sciences, which, being once masters of, we may easily extend our conquests everywhere."

The faculties of our minds are the tools and engines we must use in every disquisition; and the better we understand their [6] nature and force, the more successfully we shall be able to apply them. Mr Locke gives this account of the occasion of his entering upon his essay concerning human understanding :-" Five or six friends," says he, "meeting at my chamber, and discoursing on a subject very remote from this, found themselves quickly at a stand by the difficulties that rose on every side. After we had for a while puzzled ourselves, without coming any nearer to a resolution of those doubts that perplexed us, it came into my thoughts that we took a wrong course; and that, before we set ourselves upon inquiries of that nature, it was necessary to examine our own abilities, and see what objects our understandings were fitted or not fitted to deal with. This I proposed to the company, who all readily assented; and thereupon it was agreed that this should be our first enquiry." If this be commonly the cause of perplexity in those disquisitions which have least relation to the mind, it must be so much more in those that have an immediate connection with it.

The sciences may be distinguished into two classes, according as they pertain to the material or to the intellectual world. The various parts of natural philosophy, the mechanical arts, chemistry, medicine, and agriculture, belong to the first; but, to the last, belong grammar, logic, rhetoric, na

Hume probably had the saying of Polybius in his eye, who calls History the mother city, (nrgoro25,) of Philosophy.-H. [6, 7]

tural theology, morals, jurisprudence, law. politics, and the fine arts. The knowledge of the human mind is the root from which these grow, and draw their nourishment. Whether, therefore, we consider the dignity of this subject, or its subserviency to science in general, and to the noblest branches of science in particular, it highly deserves to be cultivated. [7]

A very elegant writer, on the sublime and beautiful,† concludes his account of the passions thus :-"The variety of the pas sions is great, and worthy, in every branch of that variety, of the most diligent inves tigation. The more accurately we search into the human mind, the stronger traces we everywhere find of His wisdom who made it. If a discourse on the use of the parts of the body may be considered as a hymn to the Creator, the use of the passions, which are the organs of the mind, cannot be barren of praise to Him, nor unproductive to ourselves of that noble and uncommon union of science and admiration, which a contemplation of the works of infinite Wisdom alone can afford to a rational mind; whilst referring to Him whatever we find of right, or good, or fair, in ourselves, discovering His strength and wisdom even in our own weakness and imperfection, honouring them where we discover them clearly, and adoring their profundity where we are lost in our search, we may be inquisitive without impertinence, and elevated without pride; we may be admitted, if I may dare to say so, into the counsels of the Almighty, by a consideration of his works. This ele vation of the mind ought to be the principal end of all our studies, which, if they do not in some measure effect, they are of very little service to us."

It is justly observed by M. Jouffroy, that the division here enounced is not in principle identical with that previously propounded.-H. + Burke.-H.

Galen is referred to.-H.

CHAPTER I.

EXPLICATION OF WORDS.

THERE is no greater impediment to the advancement of knowledge than the ambiguity of words. To this chiefly it is owing that we find sects and parties in most branches of science; and disputes which are carried on from age to age, without being brought to an issue.

Sophistry has been more effectually excluded from mathematics and natural philosophy than from other sciences. In mathematics it had no place from the beginning; mathematicians having had the wisdom to define accurately the terms they use, and to lay down, as axioms, the first principles on which their reasoning is grounded. Accordingly, we find no parties among mathematicians, and hardly any disputes.[10] In natural philosophy, there was no less sophistry, no less dispute and uncertainty, than in other sciences, until, about a century and a half ago, this science began to be built upon the foundation of clear definitions and self-evident axioms. Since that time, the science, as if watered with the dew of Heaven, hath grown apace; disputes have ceased, truth hath prevailed, and the science hath received greater increase in two centuries than in two thousand years before.

It were to be wished that this method, which hath been so successful in those branches of science, were attempted in others; for definitions and axioms are the foundations of all science. But that definitions may not be sought where no definition can be given, nor logical definitions be attempted where the subject does not admit of them, it may be proper to lay down some general principles concerning definition, for

It was not the superior wisdom of mathema. ticians, but the simple and palpable character of their object-matter, which determined the difference.-H.

the sake of those who are less conversant in this branch of logic.

When one undertakes to explain any art or science, he will have occasion to use many words that are common to all who use the same language, and some that are peculiar to that art or science. Words of the last kind are called terms of the art, and ought to be distinctly explained, that their meaning may be understood.

A definition is nothing else but an explication of the meaning of a word, by words whose meaning is already known. Hence it is evident that every word cannot be defined; for the definition must consist of words; and there could be no definition, if there were not words previously understood without definition. Common words, therefore, ought to be used in their common acceptation; and, when they have different acceptations in common language, these, when it is necessary, ought to be distinguished. But they require no definition. It is sufficient to define words that are uncommon, or that are used in an uncommon meaning.

It may farther be observed, that there are many words, which, though they may need explication, cannot be logically defined. A[11] logical definition-that is, a strict and proper definition-must express the kind [genus] of the thing defined, and the specific difference by which the species defined is distinguished from every other species belonging to that kind. It is natural to the mind of man to class things under various kinds, and again to subdivide every kind into its various species. A species may often be subdivided into subordinate species, and then it is considered as a kind.

From what has been said of logical definition, it is evident, that no word can be logically defined which does not denote a

In what follows, there is a confusion of defini tions verbal and real, which should have been carefully distinguished.-H.

species; because such things only can have a specific difference; and a specific difference is essential to a logical definition. On this account there can be no logical definition of individual things, such as London or Paris. Individuals are distinguished either by proper names, or by accidental circumstances of time or place; but they have no specific difference; and, there fore, though they may be known by proper names, or may be described by circumstances or relations, they cannot be defined. It is no less evident that the most general words cannot be logically defined, because there is not a more general term, of which they are a species.

Nay, we cannot define every species of things, because it happens sometimes that we have not words to express the specific difference. Thus, a scarlet colour is, no doubt, a species of colour; but how shall we express the specific difference by which scarlet is distinguished from green or blue? The difference of them is immediately perceived by the eye; but we have not words to express it. These things we are taught by logic.

Without having recourse to the principles of logic, we may easily be satisfied that words cannot be defined, which signify things perfectly simple, and void of all composition. This observation, I think, was first made by Des Cartes, and afterwards more fully illustrated by Locke.† And, however obvious it appears to be, many instances may be given of great philosophers who have perplexed [12] and darkened the subjects they have treated, by not knowing, or not attending to it.

When men attempt to define things which cannot be defined, their definitions will always be either obscure or false. It was one of the capital defects of Aristotle's philosophy, that he pretended to define the simplest things, which neither can be, nor need to be defined-such as time and motion. Among modern philosophers, I

*It is well said by the old logicians, Omnis intuitiva notitia est definitio;-that is, a view of the thing itself is its best definition. And this is true, both of the objects of sense, and of the objects of self. consciousness.-H.

This is incorrect. Des Cartes has little, and Locke no title to praise for this observation. It had been made by Aristotle, and after him by many others; while, subsequent to Des Cartes, and previous to Locke, Pascal and the Port-Royal Logicians, to say nothing of a paper of Leibnitz, in 1684, had reduced it to a matter of commonplace. In this instance, Locke can, indeed, be proved a borrower. Mr Stewart ("Philosophical Essays," Note A) is wrong in think. ing that, after Des Cartes, Lord Stair is the earliest philosopher by whom this logical principle was

enounced; for Stair, as a writer, is subsequent to the authors adduced --H.

There is not a little, however, to be said in vindicat on of Aristotle's definitions. Leibnitz is not the only modern philosopher who has applauded that of Motion, which requires, however, some ills. tration of the special significance of its terms.-H.

know none that has abused definition so much as Carolus [Christianus] Wolfius, the famous German philosopher, who, in a work on the human mind, called "Psychologia Empirica," consisting of many hundred propositions, fortified by demonstrations, with a proportional accompani ment of definitions, corollaries, and scholia, has given so many definitions of things which cannot be defined, and so many demonstrations of things self-evident, that the greatest part of the work consists of tautology, and ringing changes upon words.

There is no subject in which there is more frequent occasion to use words tha cannot be logically defined, than in treating of the powers and operations of the mind. The simplest operations of our minds must all be expressed by words of this kind. No man can explain, by a logical definition, what it is to think, to apprehend, to believe, to will, to desire. Every man who under stands the language, has some notion of the meaning of those words; and every man who is capable of reflection may, by attending to the operations of his own mind, which are signified by them, form a clear and distinct notion of them; but they cannot be logically defined.

Since, therefore, it is often impossible to define words which we must use on this subject, we must as much as possible use common words, in their common acceptation, pointing out their various senses where they are ambiguous; and, when we aro obliged to use words less common, we must endeavour to explain them [13] as well as we can, without affecting to give logical de finitions, when the nature of the thing does not allow it.

The following observations on the meaning of certain words are intended to supply, as far as we can, the want of definitions, by preventing ambiguity or obscurity in the use of them.

1. By the mind of a man, we understand that in him which thinks, remembers, rea sons, wills. The essence both of body and of mind is unknown to us. We know certain properties of the first, and certain operations of the last, and by these only we can define or describe them. We define body to be that which is extended, solid, moveable, divisible. In like manner, we define mind to be that which thinks. We are concious that we think, and that we have a variety of thoughts of different kinds-such as sceing, hearing, remembering, deliberating, resolving, loving, hating, and many

other kinds of thought-all which we are taught by nature to attribute to one internal principle; and this principle of thought we call the mind or soul of a man.

2. By the operations" of the mind, we understand every mode of thinking of which we are conscious.

It deserves our notice, that the various modes of thinking have always, and in all languages, as far as we know, been called by the name of operations of the mind, or by names of the same import. To body we ascribe various properties, but not operations, properly so called: it is extended, divisible, moveable, inert; it continues in any state in which it is put; every change of its state is the effect of some force impressed upon it, and is exactly proportional to the force impressed, and in the precise direction of that force. These are the general properties of matter, and these are not operations; on the contrary, they all imply its being a dead, inactive thing, which moves only as it is moved, and acts only by being acted upon.† [14]

But the mind is, from its very nature, a living and active being. Everything we know of it implies life and active energy; and the reason why all its modes of thinking are called its operations, is, that in all, or in most of them, it is not merely passive, as body is, but is really and properly active.

In all ages, and in all languages, ancient and modern, the various modes of thinking have been expressed by words of active signification, such as seeing, hearing, reasoning, willing, and the like. It seems, therefore, to be the natural judgment of mankind, that the mind is active in its various ways of thinking: and, for this reason, they are called its operations, and are expressed by active verbs.

It may be made a question, What regard is to be paid to this natural judgment? May it not be a vulgar error? Philosophers who think so have, no doubt, a right to be heard. But, until it is proved that the mind is not active in thinking, but merely passive, the common language with regard to its operations ought to be used, and ought not to give place to a phraseology invented by philosophers, which implies its being merely passive.

3. The words power and faculty, which are often used in speaking of the mind, need little explication. Every operation supposes a power in the being that operrates; for to suppose anything to operate, which has no power to operate, is manifestly absurd. But, on the other hand,

Operation, Act, Energy, are nearly convertible terms; and are opposed to Faculty, (of which anon,) as the actual to the potential -H.

"Materiae datum est cogi, sed cogere Menti." MANILIUS.-H.

there is no absurdity in supposing a being to have power to operate, when it does not operate. Thus I may have power to walk, when I sit; or to speak, when I am silent. Every operation, therefore, implies power; but the power does not imply the operation.

The faculties of the mind, and its powers, are often used as synonymous expressions. But, as most synonymes have some minute distinction that deserves notice, I apprehend that the word faculty [15] is most properly applied to those powers of the mind which are original and natural, and which make a part of the constitution of the mind. There are other powers, which are acquired by use, exercise, or study, which are not called faculties, bat habits. There must be something in the constitution of the mind necessary to our being able to acquire habitsand this is commonly called capacity.

4. We frequently meet with a distinction in writers upon this subject, between things in the mind, and things external to the mind. The powers, faculties, and operations of the mind, are things in the mind. Everything is said to be in the mind, of which the mind is the subject. It is self-evident that there are some things which cannot exist without a subject to which they belong, and of which they are attributes. Thus, colour must be in something coloured; figure in something figured; thought can only be in something that thinks; wisdom and virtue cannot exist but in some being that is wise and virtuous. When, therefore, we speak of things in the mind, we understand by this, things of which the mind is the subject. Excepting the mind itself, and things in the mind, all other things are said to be external. It ought therefore to be remembered, that this distinction between things in the mind and things external, is not meant to signify the place of the things we speak of, but their subject.†

There is a figurative sense in which things are said to be in the mind, which it is sufficient barely to mention. We say such a thing was not in my mind; meaning no more than that I had not the least thought of it. By a figure, we put the thing for the thought

These terms properly stand in the following re lations:-Powers are active and passive, natural and acquired. Powers, natural and active, are called Faculties: Powers, natural and passive, Capacities habit is used both in an active and in a passive sense: or Receptivities: Powers acquired are Habits, and the Power, again, of acquiring a habit, is called a further, under the first Essay on the Active Powers, Disposition. On the meaning of the term Power, see chap. iii, p 23-H

+ Subject and object are correlative terms. The former is properly id in quo: the latter, id circa quod. Hence, in psychological language, the subject, absolutely, is the mind that knows or thinks-i e., the mind considered as the subject of knowledge or thought; the object, that which is known, or thought about. The adjectives subjective and objective_are convenient, if not indispensable, expressions.-H.

of it. In this sense external things are in the mind as often as they are the objects of our thought.

5. Thinking is a very general word, which includes all the operations of our minds, and is so well understood as to need no definition. [16]

To perceive, to remember, to be conscious, and to conceive or imagine, are words common to philosophers and to the vulgar. They signify different operations of the mind, which are distinguished in all languages, and by all men that think. I shall endeavour to use them in their most common and proper acceptation, and I think they are hardly capable of strict definition. But, as some philosophers, in treating of the mind, have taken the liberty to use them very improperly, so as to corrupt the English language, and to confound things which the common understanding of mankind hath always led them to distinguish, I shall make some observations on the meaning of them, that may prevent ambiguity or confusion in the use of them.

6. First, We are never said 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 horse; but no man says that he perceives such a creature of imagination. Thus perception is distinguished from conception or imagination. Secondly, Perception is applied only to external objects, not to those that are in the mind itself. When I am pained, I do not say that I perceive pain, but that I feel it, or that I am conscious of it. Thus, perception is distinguished from consciousness. Thirdly, The immediate object of perception must be something present, and not what is past. We may remember what is past, but do not perceive it. I may say, I perceive such a person has had the small-pox; but this phrase is figurative, although the figure is so familiar that it is not observed. The meaning of it is, that I perceive the pits in his face, which are certain signs of his having had the small pox. We say we perceive the thing signified, when we only perceive the sign. But when the word perception is used properly, and without any figure, it is never applied to things past. And thus it is distinguished from remembrance.

In a word, perception is most properly applied to the evidence which we have of external objects by our senses. But, as this is a [17] very clear and cogent kind of evidence, the word is often applied by analogy to the evidence of reason or of testi

Thought and thinking are used in a more, and in a less, restricted signification. In the former mean. ing they are limited to the discursive energies alone; in the latter, they are co-extensive with consciousness.-H.

mony, when it is clear and cogent. The perception of external objects by our senses, is an operation of the mind of a peculiar nature, and ought to have a name appropriated to it. It has so in all languages. And, in English, I know no word more proper to express this act of the mind than perception. Seeing, hearing, smelling, tasting, and touching or feeling, are words that express the operations, proper to each sense; perceiving expresses that which is common to them all.

The observations made on this word would have been unnecessary, if it had not been so much abused in philosophical writings upon the mind; for, in other writings, it has no obscurity. Although this abuse is not chargeable on Mr Hume only, yet I think he has carried it to the highest pitch. The first sentence of his "Treatise of Human Nature" runs thus :-"All the perceptions of the human mind resolve themselves into two distinct heads, which I shall call impressions and ideas." He adds, a little after, that, under the name of impressions, he comprehends all our sensations, passions, and emotions. Here we learn that our passions and emotions are perceptions. I believe, no English writer before him ever gave the name of a perception to any passion or emotion. When a man is angry, we must say that he has the perception of anger. When he is in love, that he has the perception of love. He speaks often of the perceptions of memory, and of the perceptions of imagination; and he might as well speak of the hearing of sight, or of the smelling of touch; for, surely, hearing is not more different from sight, or smelling from touch, than perceiving is from remembering or imagin ing.

7. Consciousness is a word used by philosophers, to signify that immediate knowledge which we have of our present thoughts and purposes, and, in general, of all the present operations of our minds. Whence we may observe, that consciousness is only of things present. To apply consciousness to things past, which sometimes [18] is done in popular discourse, is to confound consciousness with memory; and all such confusion of words ought to be avoided in philosophical discourse. It is likewise to be observed, that consciousness

In the Cartesian and Lockian philosophies, the term Perception was used almost convertibly with Consciousness: whatever we could be said to be conscious of, that we could be said to perceive. And there is nothing in the etymology of the word, or in its use by ancient writers, that renders this unexclu sive application of it abusive. In the Leibnitzian philosophy, perception and apperception were distinguished in a peculiar manner-of which again, Reid is right in his own restriction of the term; but he is not warranted in blaming Hume for having used it in the wider signification of his predecessors.-H.