tention to philosophers; it has been analysed into its very elements of subject, predicate, and copula. All the various modifications of these, and of propositions which are compounded of them, have been anxiously examined in many voluminous tracts. The expression of a question, of a command, or of a promise, is as capable of being analysed as a proposition is; but we do not find that this has been attempted; we have not so much as given them a name different from the operations which they

express.

Why have speculative men laboured so anxiously to analyse our solitary operations, and given so little attention to the social? I know no other reason but this, that in the divisions that have been made of the mind's operations, the social have been omitted, and thereby thrown behind the curtain.

In all languages, the second person of verbs, the pronoun of the second person, and the vocative case in nouns, are appropriated to the expression of social operations of mind, and could never have had place in language but for this purpose; nor is it a good argument against this observation, that, by a rhetorical figure, we sometimes address persons that are absent, or even inanimated beings, in the second person. For it ought to be remembered that all figurative ways of using words or phrases suppose a natural and literal meaning of them.

ESSAY II.

ON THE POWERS WE HAVE BY MEANS OF OUR EXTERNAL SENSES.

CHAPTER I.

OF THE ORGANS OF SENSE.

Of all the operations of our minds, the perception of external objects is the most familiar. The senses come to maturity even in infancy, when other powers have not yet sprung up. They are common to us with brute animals, and furnish us with the objects about which our other powers are the most frequently employed. We find it easy to attend to their operations; and because they are familiar, the names which properly belong to them are applied to other powers, which are thought to resemble them; for these reasons they claim to be first considered.

The perception of external objects is one main link of that mysterious chain, which connects the material world with the intellectual. We shall find many things in this operation unaccountable; sufficient to convince us, that we know but little of our own frame; and that a perfect comprehension of our mental powers, and of the manner of their operation, is beyond the reach of our understanding.

In perception there are impressions upon the organs of sense, the nerves, and brain, which, by the laws of our nature, are followed by certain operations of mind. These two things are apt to be confounded; but ought most carefully to be distinguished. Some philosophers, without good reason, have concluded, that the impressions made on the body are the proper efficient cause of perception. Others, with as little reason, have concluded, that impressions are made on the mind similar to those made on the body. From these mistakes many others have arisen. The wrong notions men have rashly taken up with regard to the senses have led to wrong notions with regard to other powers which are conceived to resemble them. Many important powers of mind have, especially of late, been called internal senses, from a supposed resemblance to the external; such as, the sense of beauty, the sense of harmony, the moral sense. And it is to be apprehended, that errors, with regard to the external, have, from analogy, led to similar errors with regard to the internal; it is therefore of some consequence, even with regard to other branches of our subject, to have just notions concerning the external senses.

In order to this, we shall begin with some observations on the organs of sense, and on the impressions which in perception are made upon them, and upon the nerves and brain.

We perceive no external object, but by means of certain bodily organs which God has given us for that purpose. The Supreme Being who made us, and placed us in this world, hath given us such powers of mind as he saw to be suited to our state and rank in his creation. He has given us the power of perceiving many objects around us, the sun, moon, and

stars, the earth and sea, and a variety of animals, vegetables, and inanimate bodies. But our power of perceiving these objects is limited in various ways, and particularly in this, that without the organs of the several senses, we perceive no external object. We cannot see without eyes, nor hear without ears: it is not only necessary that we should have these organs, but that they should be in a sound and natural state. There are many disorders of the eye that cause total blindness; others that impair the powers of vision, without destroying it altogether; and the same may be said of the organs of all the other senses.

All this is so well known from experience, that it needs no proof: but it ought to be observed, that we know it from experience only. We can give no reason for it, but that such is the will of our Maker. No man can show it to be impossible to the Supreme Being to have given us the power of perceiving external objects without such organs. We have reason to believe, that when we put off these bodies, and all the organs belonging to them, our perceptive powers shall rather be improved than destroyed or impaired. We have reason to believe, that the Supreme Being perceives every thing in a much more perfect manner thran we do, without bodily organs. We have reason to believe, that there are other created beings endowed with powers of perception more perfect and more extensive than ours, without any such organs as we find necessary.

We ought not, therefore, to conclude, that such bodily organs are, in their own nature, necessary to perception; but rather, that, by the will of God, our power of perceiving external objects is limited and circumscribed by our organs of sense; so that we perceive objects in a certain manner, and in certain circumstances, and in no other.

If a man was shut up in a dark room, so that he could see nothing but through one small hole in the shutter of a window, would he conclude, that the hole was the cause of his seeing, and that it is impossible to see any other way? Perhaps if he had never in his life seen but in this way, he might be apt to think so; but the conclusion is rash and groundless. He sees, because God has given him the power of seeing; and he sees only through this small hole, because his power of seeing is circumscribed by impediments on all other hands.

Another necessary caution in this matter is, that we ought not to confound the organs of perception with the being that perceives. Perception must be the act of some being that perceives. The eye is not that which sees; it is only the organ by which we see. The ear is not that which hears; but the organ by which we hear; and so of the rest.

A man cannot see the satellites of Jupiter but by a telescope. Does he conclude from this, that it is the telescope that sees those stars? by no means; such a conclusion would be absurd. It is no less absurd to conclude, that it is the eye that sees, or the ear that hears. The telescope is an artificial organ of sight, but it sees not. The eye is a natural organ of sight, by which we see; but the natural organ sees as little as the artificial.

The eye is a machine most admirably contrived for refracting the rays of light, and forming a distinct picture of objects upon the retina; but it sees neither the object nor the picture. It can form the picture after it is taken out of the head; but no vision ensues. Even when it is in its proper place, and perfectly sound, it is well known, that an obstruction in the optic nerve takes away vision, though the eye has performed all that belongs to it.

If any thing more were necessary to be said on a point so evident, we

might observe, that if the faculty of seeing were in the eye, that of hearing in the ear, and so of the other senses, the necessary consequence of this would be, that the thinking principle, which I call myself, is not one, but many. But this is contrary to the irresistible conviction of every man. When I say, I see, I hear, I feel, I remember, this implies that it is one and the same self that performs all these operations; and as it would be absurd to say, that my memory, another man's imagination, and a third man's reason, may make one individual intelligent being, it would be equally absurd to say, that one piece of matter seeing, another hearing, and a third feeling, may make one and the same percipient being.

These sentiments are not new; they have occurred to thinking men from early ages. Cicero, in his Tusculan Questions, lib. i. chap. 28. has expressed them very distinctly. Those who choose may consult the

passage.

CHAPTER II.

OF THE IMPRESSIONS ON THE ORGANS, NERVES, AND BRAINS.

A SECOND law of our nature regarding perceptions is, that we perceive no object, unless some impression is made upon the organ of sense, either by the immediate application of the object, or by some medium which passes between the object and the organ.

In two of our senses, to wit, touch and taste, there must be an immediate application of the object to the organ. In the other three, the object is perceived at a distance, but still by means of a medium, by which some impression is made upon the organ.

The effluvia of bodies drawn into the nostrils with the breath, are the medium of smell: the undulations of the air, are the medium of hearing; and the rays of light passing from visible objects to the eye, are the medium of sight. We see no object, unless rays of light come from it to the eye. We hear not the sound of any body, unless the vibrations of some elastic medium, occasioned by the tremulous motion of the sounding body, reach our ear. We perceive no smell, unless the effluvia of the smelling body enter into the nostrils. We perceive no taste, unless the sapid body be applied to the tongue, or some part of the organ of taste. Nor do we perceive any tangible quality of a body, unless it touch the hand, or some part of our bodies.

These are facts known from experience to hold universally and invariably, both in men and brutes. By this law of our nature, our powers of perceiving external objects are farther limited and circumscribed. Nor can we give any other reason for this, than that it is the will of our Maker, who knows best what powers, and what degrees of them, are suited to our state. We were once in a state, I mean in the womb, wherein our powers of perception were more limited than in the present, and, in a future state, they may be more enlarged.

It is likewise a law of our nature, that, in order to our perceiving objects, the impressions made upon the organs of sense must be communicated to the nerves, and by them to the brain. This is perfectly known to those who know any thing of anatomy.

The nerves are fine cords, which pass from the brain, or from the spinal marrow, which is a production of the brain, to all parts of the body, dividing into smaller branches as they proceed, until at last they escape our eye-sight: And it is found by experience, that all the voluntary and

When the

involuntary motions of the body are performed by their means. nerves that serve any limb, are cut, or tied hard, we have then no more power to move that limb than if it was no part of the body.

As there are nerves that serve the muscular motions, so there are others that serve the several senses; and as without the former we cannot move a limb, so without the latter we can have no perception.

This train of machinery the wisdom of God has made necessary to our perceiving objects. Various parts of the body concur to it, and each has its own function. First, The object either immediately, or by some medium, must make an impression on the organ. The organ serves only as a medium, by which an impression is made on the nerve; and the nerve serves as a medium to make an impression upon the brain. Here the material part ends; at least we can trace it no farther; the rest is all intellectual.

The proof of these impressions upon the nerves and brain in perception is this, That, from many observations and experiments, it is found, that when the organ of any sense is perfectly sound, and has the impression made upon it by the object ever so strongly; yet, if the nerve which serves that organ be cut or tied hard, there is no perception; and it is well known, that disorders in the brain deprive us of the power of perception, when both the organ and its nerve are sound.

There is therefore sufficient reason to conclude, that in perception, the object produces some change in the organ; that the organ produces some change upon the nerve; and that the nerve produces some change in the brain. And we give the name of an impression to those changes, because we have not a name more proper to express, in a general manner, any change produced in a body, by an external cause, without specifying the nature of that change. Whether it be pressure, or attraction, or repulsion, or vibration, or something unknown, for which we have no name, still it may be called an impression. But with regard to the particular kind of this change or impression, philosophers have never been able to discover any thing at all.

But, whatever be the nature of those impressions upon the organs, nerves, and brain, we perceive nothing without them. Experience informs that it is so; but we cannot give a reason why it is so. In the constitution of man, perception, by fixed laws of nature, is connected with those impressions; but we can discover no necessary connexion. The Supreme Being has seen fit to limit our power of perception; so that we perceive not without such impressions: and this is all we know of the

matter.

This, however, we have reason to conclude in general, that as the impressions on the organs, nerves, and brain, correspond exactly to the nature and conditions of the objects by which they are made; so our perceptions and sensations correspond to those impressions, and vary in kind, and in degree, as they vary. Without this exact correspondence, the information we receive by our senses would not only be imperfect, as it undoubtedly is, but would be fallacious, which we have no reason to think it is.