has the shape and colour of an apple: this is true. The sense of smelling testifies that it has the smell of an apple: this is likewise true, and is no deception. Where then lies the deception? It is evident it lies in this, that because this body has some qualities belonging to an apple, I conclude that it is an apple. This is a fallacy, not of the senses, but of inconclusive reasoning. "*

§. 79. Of mistakes in judging of the motion of objects.

"Many false judgments, (continues the same judicious writer,) that are accounted deceptions of sense, arise from our mistaking relative motion for real or absolute motion. These can be no deceptions of sense, because by our senses we perceive only the relative motions of the bodies; and it is by reasoning that we infer the real from the relative which we perceive. A little reflection may satisfy us of

this.

"It was before observed, that we perceive extension to be one sensible quality of bodies, and thence are necessarily led to conceive space, though space be of itself no object of sense. When a body is removed out of its place, the space which it filled remains empty till it is filled by some other body, and would remain if it should never be filled. Before any body existed, the space which bodies now occupy was empty space, capable of receiving bodies, for no body can exist where there is no space to contain it. There is space therefore wherever bodies exist, or can exist.

"Hence it is evident that space can have no limits. It is no less evident that it is immovable. Bodies placed in it are movable, but the place where they were cannot be moved; and we can as easily conceive a thing to be moved from itself, as one part of space brought nearer to, or removed further from another.

"This space, therefore, which is unlimited and immovable, is called by philosophers absolute space. Absolute, or real motion, is a change of place in absolute space.

*Reid's Intellectual Powers of Man, Essay II.

"Our senses do not testify the absolute motion or absolute rest of any body. When one body removes from another this may be discerned by the senses; but whether any body keeps the same part of absolute space, we do not perceive by our senses. When one body seems to remove from another, we can infer with certainty that there is absolute motion, but whether in the one or the other, or partly in both is not discerned by sense.

"Of all the prejudices which philosophy contradicts, I believe there is none so general as that the earth keeps its place unmoved. This opinion seems to be universal, till it is corrected by instruction, or by philosophical speculation. Those who have any tincture of education are not now in danger of being held by it, but they find at first a reluctance to believe that there are antipodes; that the earth is spherical, and turns round on its axis every day, and round the sun every year. They can recollect the time when reason struggled with prejudice upon these points, and prevailed at length, but not without some effort.

"The cause of a prejudice so very general is not unworthy of investigation. But that is not our present business. It is sufficient to observe, that it cannot justly be called a fallacy of sense; because our senses testify only the change of the situation of one body in relation to other bodies, and not its change of situation in absolute space. It is only the relative motion of bodies that we perceive, and that we perceive truly. It is the province of reason and philosophy, from the relative motions which we perceive, to collect the real and absolute motions which produce them.

"All motion must be estimated from some point or place, which is supposed to be at rest. We perceive not the points of absolute space from which real and absolute motions must be reckoned: and there are obvious reasons that lead mankind in the state of ignorance, to make the earth the fixed place from which they may estimate the various motions they perceive. The custom of doing this from infancy, and of using constantly a language which supposes the earth to be at rest, may perhaps

be the cause of the general prejudice in favor of this opinion.

"Thus it appears, that if we distinguish accurately between what our senses really and naturally testify, and the conclusions which we draw from their testimony, by reasoning, we shall find many of the errors, called fallacies of the senses, to be no fallacy of the senses, but rash judgments, which are not to be imputed to our senses.

§. 80. Of mistakes as to the distances and magnitude of

objects.

One class of the fallacies by means of the senses is made up of those errours we commit in our perceptions of the distance of objects. Our sight, it is said, often represents objects to be near which are distant, and objects. to be distant, which are near. That we often form erroneous judgments as to the distance of objects is true; but it is a mistaken sentiment, which ascribes these erroneous opinions exclusively to the misrepresentations of the sight, or of any other sense. The subject of distance will shortly come up again; and we shall therefore anticipate it only so far as to remark, that the perception of distance is not an original act of the sight, but is something acquired. We are not properly said to see distance, but rather to judge of distance by sight; and hence the data, furnished by that sense, may be right, and still the conclusions deduced from them be wrong.

II,-Another class of errours are those of magnitude. The notions, which we form on that subject also, are acquired, and not original. We judge objects to be great or small in comparison with ourselves or with one another; and not in consequence of any thing, which is directly and immediately perceived in the objects themselves. We might call many objects small, which happened to be of the size of a particular diamond, and yet not inconsistently speak of the diamond itself as a very large one; and this for the simple reason, that our notions of large and small are not absolute but relative, and are formed by repeated acts of comparison. If there were but one object in creation beside ourselves, and if we could

not reason from ourselves to that object, we could not possibly form any notion of its magnitude as distinct from the mere idea of extension. It is very clear our senses could not of themselves authorize us to speak of such an object as large or small. Nor could it be done by reasoning, inasmuch as there are supposed to be no other objects, with which to compare it.-These few remarks, the correctness of which may more fully appear hereafter, will suffice to evince, that such mistakes, as may exist in regard to the distance and magnitude of objects, are not exclusively attributable to the senses.

§. 81. The senses liable to be diseased.

There is one respect, however, in which it is perhaps true, that we can speak with propriety of deceptions, arising from the cause now under consideration. The body as a whole being liable to be diseased, the senses as a part of the physical system are of course not exempted from this liability. As a mere question of fact, it cannot be deemed a matter of doubt, that the senses are often physically disordered; and at such times all persons are liable to be led astray by them. What is sweet to persons ordinarily, may appear bitter to one with a diseased palate; what is white to the mass of mankind may appear of a yellow hue to one, whose organ of sight is diseased; the physical condition of the sense of touch may be so perverted as to lead the diseased person to imagine he is made of glass or feathers instead of flesh and blood.

But it is surely enough to say, in respect to cases of this kind, that such is the condition of humanity, the common allotment, stamped both upon body and mind, and on all their powers; and he, who knows it not, has, in great likelihood, studied more carefully the powers and excellencies, than the infirmities of human nature.

What principle in our mental constitution is not liable to be perverted? What susceptibility is not liable to find its action suspended? What strength is there, that may not be weakened? Or what beauty that may not be deformed? In all our conduct we rely, and very correctly,

on the MEMORY, but the laws, which sustain that inestimable faculty, will sometimes grow weary, inconstant, and treacherous. We rely with equal readiness on the REASONING power; no one doubts, that its conclusions are a ground of belief. But what is reasoning, when uttered in the ravings of a madman, or 'when drawing its conclusions in a lunatic asylum?

It follows, therefore, if the senses deceive us in the case. we are now attending to, the fault, if such it is to be considered, is not an exclusive one. It belongs to other parts of our nature also, not excepting its noblest and most efficient characteristics.

§. 82. Our knowledge of the material world from the senses.

It will be noticed, that, in what has been said, we have taken for granted the actual existence of an external material world; and we may add here, that it is by means of the senses we have a knowledge of such existence. It would have been premature to have adverted particularly to this subject, without first noticing and disposing of the objection, that the senses are not entitled to our reliance. From what has been brought forward, it clearly appears, that the position of their leading us astray does not hold good when we separate the proper objects of them from what are not, and when we guide and carry out the intimations of one sense by the aids of the others and of the reasoning power.

In respect to the topic now especially to be considered, it may perhaps be said with confidence, that no man, who employs the senses at all, can doubt of the real existence of an external, material creation. All external nature is operating upon us from the very moment of our birth; and giving origin, consistency, and strength to this belief. The resistance, which bodies present to the touch, when that sense is impressed upon them by the agency of the muscles, probably gives occasion for the distinct and essential idea of externality; and with this idea the senses soon enable us to associate others, as extension, colour, form, and all material qualities and properties. In this