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CHAPTER V.

OF PERCEPTION.

IN speaking of the impressions made on our organs in perception, we build upon facts borrowed from anatomy and physiology, for which we have the testimony of our senses. But, being now to speak of perception itself, which is solely an act of the mind, we must appeal to another authority. The operations of our minds are known, not by sense, but by consciousness, the authority of which is as certain and as irresistible as that of sense.

In order, however, to our having a distinct notion of any of the operations of our own minds, it is not enough that we be conscious of them; for all men have this consciousness. It is farther necessary that we attend to them while they are exerted, and reflect upon them with care, while they are recent and fresh in our memory. It is necessary that, by employing ourselves frequently in this way, we get the habit of this attention and reflection; and, therefore, for the proof of facts which I shall have occasion to mention upon this subject, I can only appeal to the reader's own thoughts, whether such facts are not agreeable to what he is conscious of in his own mind. [106]

If, therefore, we attend to that act of our mind which we call the perception of an external object of sense, we shall find in it these three things:-First, Some conception or notion of the object perceived; Secondly, A strong and irresistible conviction and belief of its present existence; and, Thirdly, That this conviction and belief are immediate, and not the effect of reasoning."

First, It is impossible to perceive an object without having some notion or conception of that which we perceive. We may, indeed, conceive an object which we do not perceive; but, when we perceive the object, we must have some conception of it at the same time; and we have commonly a more clear and steady notion of the object while we perceive it, than we have from memory or imagination when it is not perceived. Yet, even in perception, the notion which our senses give of the object may be more or less clear, more or less distinct, in all possible degrees.

Thus we see more distinctly an object at a small than at a great distance. An object at a great distance is seen more distinctly in

losophabitur nullamque hujus rei ideam habere poterit. Si vero ad Deum Creatorem adscendamus, eumque vere agnoscamus, nihil hic erit obscuri, hunc effectum clarissime intelligemus, et quidem per caussam ejus primam; quæ perfectissima demum est scientia."-H.

See above, p. 183, a, note; p. 128, b, note *; and Note C.-H.

An object

a clear than in a foggy day. seen indistinctly with the naked eye, on account of its smallness, may be seen distinctly with a microscope. The objects in this room will be seen by a person in the room less and less distinctly as the light of the day fails; they pass through all the various degrees of distinctness according to the degrees of the light, and, at last, in total darkness they are not seen at all. What has been said of the objects of sight is so easily applied to the objects of the other senses, that the application may be left to the reader.

In a matter so obvious to every person capable of reflection, it is necessary only farther to observe, that the notion which we get of an object, merely by our external sense, ought not to be confounded with that more scientific notion which a man, come to the years of understanding, may have of the same object, by attending to its various attributes, or to its various parts, and their relation to each other, and to the whole. [107] Thus, the notion which a child has of a jack for roasting meat, will be acknowledged to be very different from that of a man who understands its construction, and perceives the relation of the parts to one another, and to the whole. The child sees the jack and every part of it as well as the man. The child, therefore, has all the notion of it which sight gives; whatever there is more in the notion which the man forms of it, must be derived from other powers of the mind, which may afterwards be explained. This observation is made here only that we may not confound the operations of different powers of the mind, which by being always conjoined after we grow up to understanding, are apt to pass for one and the same.

Secondly, In perception we not only have a notion more or less distinct of the object perceived, but also an irresistible conviction and belief of its existence. This is always the case when we are certain that we perceive it. There may be a perception so faint and indistinct as to leave us in doubt whether we perceive the object or not. Thus, when a star begins to twinkle as the light of the sun withdraws, one may, for a short time, think he sees it without being certain, until the perception acquire some strength and steadiness. When a ship just begins to appear in the utmost verge of the horizon, we may at first be dubious whether we perceive it or not; but when the perception is in any degree clear and steady, there remains no doubt of its reality; and when the reality of the perception is ascertained, the existence of the object perceived can no longer be doubted.

In this paragraph there is a confusion of that which is perceived and that which is inferred from the perception.-H.

state. General rules that regard those whose intellects are sound are not overthrown by instances of men whose intellects are hurt by any constitutional or accidental disorder.

By the laws of all nations, in the most by various accidents, be reduced to this solemn judicial trials, wherein men's fortunes and lives are at stake, the sentence passes according to the testimony of eye or ear witnesses of good credit. An upright judge will give a fair hearing to every objection that can be made to the integrity of a witness, and allow it to be possible that he may be corrupted; but no judge will ever suppose that witnesses may be imposed upon by trusting to their eyes and ears. And if a sceptical counsel should plead against the testimony of the witnesses, that they had no other evidence for what they [108] declared but the testimony of their eyes and ears, and that we ought not to put so much faith in our senses as to deprive men of life or fortune upon their testimony, surely no upright judge would admit a plea of this kind. I believe no counsel, however sceptical, ever dared to offer such an argument; and, if it was offered, it would be rejected with disdain.

Can any stronger proof be given that it is the universal judgment of mankind that the evidence of sense is a kind of evidence which we may securely rest upon in the most momentous concerns of mankind; that it is a kind of evidence against which we ought not to admit any reasoning; and, therefore, that to reason either for or against it is an insult to common sense?

The whole conduct of mankind in the daily occurrences of life, as well as the solemn procedure of judicatories in the trial of causes civil and criminal, demonstrates this. I know only of two exceptions that may be offered against this being the universal belief of mankind.

The first exception is that of some lunatics who have been persuaded of things that seem to contradict the clear testimony of their senses. It is said there have been lunatics and hypochondriacal persons, who seriously believed themselves to be made of glass; and, in consequence of this, lived in continual terror of having their brittle frame shivered into pieces.

All I have to say to this is, that our minds, in our present state, are, as well as our bodies, liable to strange disorders; and, as we do not judge of the natural constitution of the body from the disorders or diseases to which it is subject from accidents, so neither ought we to judge of the natural powers of the mind from its disorders, but from its sound state. It is natural to man, and common to the species, to have two hands and two feet; yet I have seen a man, and a very ingenious one, who was born without either hands or feet. [109] It is natural to man to have faculties superior to those of brutes; yet we see some individuals whose faculties are not equal to those of many brutes; and the wisest man may,

The other exception that may be made to the principle we have laid down is that of some philosophers who have maintained that the testimony of sense is fallacious, and therefore ought never to be trusted. Perhaps it might be a sufficient answer to this to say, that there is nothing so absurd which some philosophers have not maintained. It is one thing to profess a doctrine of this kind, another seriously to be lieve it, and to be governed by it in the conduct of life. It is evident that a man who did not believe his senses could not keep out of harm's way an hour of his life; yet, in all the history of philosophy, we never read of any sceptic that ever stepped into fire or water because he did not believe his senses, or that shewed in the conduct of life less trust in his senses than other men have.+ This gives us just ground to apprehend that philosophy was never able to conquer that natural belief which men have in their senses; and that all their subtile reasonings against this belief were never able to persuade themselves.

It appears, therefore, that the clear and distinct testimony of our senses carries irresistible conviction along with it to every man in his right judgment.

I observed, Thirdly, That this conviction is not only irresistible, but it is immediate ; that is, it is not by a train of reasoning and argumentation that we come to be convinced of the existence of what we perceive; we ask no argument for the existence of the object, but that we perceive it; perception commands our belief upon its own authority, and disdains to rest its authority upon any reasoning whatsoever.‡ [110]

The conviction of a truth may be irresistible, and yet not immediate. Thus, my conviction that the three angles of every plain triangle are equal to two right angles, is irresistible, but it is not immediate; I am convinced of it by demonstrative reasoning. There are other truths in mathematics of which we have not only an irresistible but an immediate conviction. Such are the axioms. Our belief of the axioms in mathematics is not grounded upon argu

A saying of Varro.-H.

↑ All this we read, however, in Laërtius, of Pyrrho; and on the authority of Antigonus Carystius, the great sceptic's contemporary. Whether we are to believe the narrative is another question.-H.

If Reid holds that in perception we have only a conception of the Non-Eo in the Ego, this belief is either not the reflex of a cognition, but a blind faith, or it is mediate, as held by Stewart,-Phios. Ess. ii. c. 2.-H.

ment-arguments are grounded upon them; but their evidence is discerned immediately by the human understanding.

It is, no doubt, one thing to have an immediate conviction of a self-evident axiom; it is another thing to have an immediate conviction of the existence of what we see; but the conviction is equally immediate and equally irresistible in both cases. No man thinks of seeking a reason to believe what he sees; and, before we are capable of reasoning, we put no less confidence in our senses than after. The rudest savage is as fully convinced of what he sees, and hears, and feels, as the most expert logician. The constitution of our understanding determines us to hold the truth of a mathematical axiom as a first principle, from which other truths may be deduced, but it is deduced from none; and the constitution of our power of perception determines us to hold the existence of what we distinctly perceive as a first principle, from which other truths may be deduced; but it is deduced from none. What has been said of the irresistible and immediate belief of the existence of objects distinctly perceived, I mean only to affirm with regard to persons so far advanced in understanding as to distinguish objects of mere imagination from things which have a real existence. Every man knows that he may have a notion of Don Quixote, or of Garagantua, without any belief that such persons ever existed; and that of Julius Cæsar and Oliver Cromwell, he has not only a notion, but a belief that they did really exist. [111] But whether children, from the time that they begin to use their senses, make a distinction between things which are only conceived or imagined, and things which really exist, may be doubted. Until we are able to make this distinction, we cannot properly be said to believe or to disbelieve the existence of anything. The belief of the existence of anything seems to suppose a notion of existence-a notion too abstract, perhaps, to enter into the mind of an infant. I speak of the power of perception in those that are adult and of a sound mind, who believe that there are some things which do really exist; and that there are many things conceived by themselves, and by others, which have no existence. That such persons do invariably ascribe existence to everything which they distinctly perceive, without seeking reasons or arguments for doing so, is perfectly evident from the whole tenor of human life.

The account I have given of our perception of external objects, is intended as a faithful delineation of what every man, come to years of understanding, and capable of giving attention to what passes in his own mind, may feel in himself. In what man

ner the notion of external objects, and the immediate belief of their existence, is produced by means of our senses, I am not able to shew, and I do not pretend to shew. If the power of perceiving external objects in certain circumstances, be a part of the original constitution of the human mind, all attempts to account for it will be vain. No other account can be given of the constitution of things, but the will of Him that made them. As we can give no reason why matter is extended and inert, why the mind thinks and is conscious of its thoughts, but the will of Him who made both; so I suspect we can give no other reason why, in certain circumstances, we perceive external objects, and in others do not."

The Supreme Being intended that we should have such knowledge of the material objects that surround us, as is necessary in order to our supplying the wants of nature, and avoiding the dangers to which we are constantly exposed; and he has admirably fitted our powers of perception to this purpose. [112] If the intelligence we have of external objects were to be got by reasoning only, the greatest part of men would be destitute of it; for the greatest part of men hardly ever learn to reason; and in infancy and childhood no man can reason: Therefore, as this intelligence of the objects that surround us, and from which we may receive so much benefit or harm, is equally necessary to children and to men, to the ignorant and to the learned, God in his wisdom conveys it to us in a way that puts all upon a level. The inform ation of the senses is as perfect, and gives as full conviction to the most ignorant as to the most learned.

CHAPTER VI.

WHAT IT IS TO ACCOUNT FOR A PHÆNOMENON IN NATURE.

AN object placed at a proper distance, and in a good light, while the eyes are shut, is not perceived at all; but no sooner do we open our eyes upon it than we have, as it were by inspiration, a certain knowledge of its existence, of its colour, figure, and distance. This is a fact which every one knows. The vulgar are satisfied with knowing the fact, and give themselves no trouble about the cause of it: but a philosopher is impatient to know how this event is produced, to account for it, or assign its cause.

This avidity to know the causes of things is the parent of all philosophy, true and false. Men of speculation place a great part of their happiness in such knowledge.

See above, p. 128, b, note, and p. 130, b, note; also Note A.-H.

Felix qui potuit rerum cognoscere causas, has always been a sentiment of human nature. But, as in the pursuit of other kinds of happiness men often mistake the road, so in none have they more frequently done it than in the philosophical pursuit of the causes of things. [113]

velocity being continued through the third second, and having the same addition by gravitation as in any of the preceding, the whole velocity at the end of the third second will be thrice as great as at the end of the first, and so on continually.

We may here observe, that the causes assigned of this phænomenon are two: First, That bodies once put in motion retain their velocity and their direction, until it is changed by some force impressed upon them. Secondly, That the weight or gravitation of a body is always the same. These are laws of Nature, confirmed by universal experi

causes. Then, they are precisely adequate to the effect ascribed to them; they must necessarily produce that very motion in descending bodies which we find to take place; and neither more nor less. The account, therefore, given of this phænomnon, is just and philosophical; no other will ever be required or admitted by those who understand this.

It is a dictate of common sense, that the causes we assign of appearances ought to be real, and not fictions of human imagination. It is likewise self-evident, that such causes ought to be adequate to the effects that are conceived to be produced by them. That those who are less accustomed to inquiries into the causes of natural appear-ence, and therefore are not feigned but true ances, may the better understand what it is to shew the cause of such appearances, or to account for them, I shall borrow a plain instance of a phænomenon or appearance, of which a full and satisfactory account has been given. The phænomenon is this: That a stone, or any heavy body, falling from a height, continually increases its velocity as it descends; so that, if it acquire a certain velocity in one second of time, it will have twice that velocity at the end of two seconds, thrice at the end of three seconds, and so on in proportion to the time. This accelerated velocity in a stone falling must have been observed from the beginning of the world; but the first person, as far as we know, who accounted for it in a proper and philosophical manner, was the famous Galileo, after innumerable false and fictitious accounts had been given of it.

He observed, that bodies once put in motion continue that motion with the same velocity, and in the same direction, until they be stopped or retarded, or have the direction of their motion altered, by some force impressed upon them. This property of bodies is called their inertia, or inactivity; for it implies no more than that bodies cannot of themselves change their state from rest to motion, or from motion to rest. He observed also, that gravity acts constantly and equally upon a body, and therefore will give equal degrees of velocity to a body in equal times. From these principles, which are known from experience to be fixed laws of nature, Galileo shewed that heavy bodies must descend with a velocity uniformly accelerated, as by experience they are found to do. [114] For if the body by its gravitation acquire a certain velocity at the end of one second, it would, though its gravitation should cease that moment, continue to go on with that velocity; but its gravitation continues, and will in another second give it an additional velocity, equal to that which it gave in the first; so that the whole velocity at the end of two seconds, will be twice as great as at the end of one. In like manner, this

It ought likewise to be observed, that the causes assigned of this phænomenon, are things of which we can assign no cause. Why bodies once put in motion continue to move-why bodies constantly gravitate towards the earth with the same force-no man has been able to shew: these are facts confirmed by universal experience, and they must no doubt have a cause; but their cause is unknown, and we call them laws of Nature, because we know no cause of them, but the will of the Supreme Being.

But may we not attempt to find the cause of gravitation, and of other phænomena, which we call laws of Nature? No doubt we may. [115] We know not the limit which has been set to human knowledge, and our knowledge of the works of God can never be carried too far. But, supposing gravitation to be accounted for, by an æthereal elastic medium, for instance, this can only be done, first, by proving the existence and the elasticity of this medium; and, secondly, by shewing that this medium must necessarily produce that gravitation which bodies are known to have. Until this be done, gravitation is not accounted for, nor is its cause known; and when this is done, the elasticity of this medium will be considered as a law of nature whose cause is unknown. The chain of natural causes has, not unfitly, been compared to a chain hanging down from heaven: a link that is discovered supports the links below it, but it must itself be supported; and that which supports it must be supported, until we come to the first link, which is supported by the throne of the Almighty. Every natural cause must have a cause, until we ascend to the first cause, which is uncaused, and operates not by necessity but by will

By what has been said in this chapter, those who are but little acquainted with philosophical inquiries, may see what is meant by accounting for a phænomenon, or shewing its cause, which ought to be well understood, in order to judge of the theories by which philosophers have attempted to account for our perception of external objects by the senses.

CHAPTER VII.

SENTIMENTS OF PHILOSOPHERS ABOUT THE PERCEPTION OF EXTERNAL OBJECTS; AND, FIRST, OF THE THEORY OF FATHER MALEBRANCHE.+

How the correspondence is carried on between the thinking principle within us, and the material world without us, has always been found a very difficult problem to those philosophers who think themselves obliged to account for every phænomenon in nature. [116] Many philosophers, ancient and modern, have employed their invention to discover how we are made to perceive external objects by our senses; and there appears to be a very great uniformity in their sentiments in the main, notwithstanding their variations in particular points.

Plato illustrates our manner of perceiving the objects of sense, in this manner. He supposes a dark subterraneous cave, in which men lie bound in such a manner that they can direct their eyes only to one part of the cave: far behind, there is a light, some rays of which come over a wall to that part of the cave which is before the eyes of our prisoners. A number of persons, variously employed, pass between them and the light, whose shadows are seen by the prisoners, but not the persons themselves.

In this manner, that philosopher conceived that, by our senses, we perceive the shadows of things only, and not things themselves. He seems to have borrowed his notions on this subject, from the Pythagoreans, and they very probably from Pythagoras himself. If we make allowance for Plato's allegorical genius, his sentiments on this subject, correspond very well with

• Sentiment, as here and elsewhere employed by Reid, in the meaning of opinion, (sententia,) is not to be imitated. There are, undoubtedly, precedents to be found for such usage in English writers; and, in the French and Italian languages, this is one of the ordinary signfications of the word-H.

It is not easy to conceive by what principle the order of the history of opinions touching Perception, contained in the nine following chapters, is deter. mined. It is not chronological, and it is not systematic. Of these theories, there is a very able survey, by M. Royer Collard, among the fragments of his lectures, in the third volume of Jouffroy's "Oeuvres de Reid." That distinguished philosopher has, however, placed too great a reliance upon the accuracy of Reid.-H.

those of his scholar, Aristotle, and of the Peripatetics. The shadows of Plato may very well represent the species and phantasms of the Peripatetic school, and the ideas and impressions of modern philosophers."

This interpretation of the meaning of Plato's comparison of the cave exhibits a curious mistake, in which Reid is followed by Mr Stewart and many others, and which, it is remarkable, has never yet been detected. In the similitude in question, (which will be found in the seventh book of the Republic,) Plato is supposed to intend an illustration of the mode in which the shadows or vicarious images of external things are admitted into the mind-to typify, in short, an hypothesis of sensitive perception, On this supposition, the identity of the Platonic, Pythagorean, and Peripatetic theories of this pro cess is inferred. Nothing can, however, be more groundless than the supposition; nothing more erro. neous than the inference. By his cave, images, and shadows, Plato meant simply to illustrate the grand principle of his philosophy-that the Sensible or Ec typal world, (phænomenal, transitory, ever, or nai nov,) stands to the Noetic or Archetypal, (sub. stantial, permanent, or v,) in the same relation of comparative unreality, in which the shadows of the images of sensible existences themselves, stand to the things of which they are the dim and distant adumbrations. In the language of an illustrious poet"An nescis, quæcunque heic sunt, quæ hac nocte teguntur,

Omnia res prorsus veras non esse, sed umbras,
Aut specula, unde ad nos aliena elucet imago?
Terra quidem, et maria alta, atque his circumfuus

aer,

Et quæ consistunt ex iis, hæc omnia tenueis
Sunt umbrae, humanos quæ tanquam somnia quæ.
dam

Pertingunt animos, fallaci et imagine ludunt,
Nunquam eadem, fluxu semper variata perenni.
Sol autem, Lunæque globus, fulgentiaque astra
Cætera, sint quamvis meliori prædita vita,

Et donata ævo immortali, hæc ipsa tamen sunt Æterni specula, in quæ animus, qui est inde profec. tus,

Inspiciens, patriæ quodam quasi tactus amore,
Ardescit. Verum quoniam heic non perstat et ultra
Nescio quid sequitur secum, tacitusque requirit,
Nosse licet circum hæc ipsum consistere verum,
Non finem: sed enim esse aliud quid, cujus imago
Splendet in iis, quod per se ipsum est, et principium

esse

Omnibus æternum, ante omnem numerumque diemque;

In quo alium Solem atque aliam splendescere Lu.

nam

Adspicias, aliosque orbes, alia astra manere, Terramque, fluviosque alios, atque aera, et ignem, Et nemora, atque aliis ei rare animalia silvis,"

And as the comparison is misunderstood, so nothing can be conceived more adverse to the doctrine of Plato than the theory it is supposed to elucidate. Plotinus, indeed, formally refutes, as contrary to the Platonic, the very hypothesis thus attributed to his master. (Enn. IV., I. vi., cc. 1., 3.) The doctrine of the Platonists on this point has been almost wholly neglected; and the author among them whose work contains its most articulate developement has been so completely overlooked, both by scholars and philosophers, that his work is of the rarest, while even his name is mentioned in no history of philosophy. It is here sufficient to state, that the idea, the λéges grasinoi, the forms representative of external things, and corresponding to the species sensiles expresse of the schoolmen, were not held by the Plato. nists to be derived from without. Prior to the act of perception, they have a latent but real existence in the soul; and, by the impassive energy of the mind itself, are elicited into consciousness, on occasion of the impression (κίνησις, πάθος, ἔμβασις) made on the external organ, and of the vital form (Carizèv tides), in consequence thereof, sublimated in the animal life. The verses of Boethius, which have been so frequently mi understood, contain an accurate statement of the Platonic theory of perception. After refuting the

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