Add to this, that every impression, external and internal, passions, affections, sensations, pains and pleasures, are originally on the same footing; and that whatever other differences we may observe among them, they appear, all of them, in their true colours, as impressions or perceptions. And indeed, if we consider the matter aright, it is scarce possible it should be otherwise, nor is it conceivable that our senses should be more capable of deceiving us in the situation and relations, than in the nature of our impressions. For since all actions and sensations of the mind are known to us by consciousness, they must necessarily appear in every particular what they are, and be what they appear. Every thing that enters the mind, being in reality a perception, it is impossible any thing should to feeling appear different. This were to suppose, that even where we are most intimately conscious, we might be mistaken.

But not to lose time in examining, whether it is possible for our senses to deceive us, and represent our perceptions as distinct from ourselves, that is as external to and independent of us; let us consider whether they really do so, and whether this error proceeds from an immediate sensation, or from some other causes.

To begin with the question concerning EXTERNAL existence, it may perhaps be said, that setting aside the metaphysical question of the identity of a thinking substance, our own body evidently belongs to us; and as several impressions appear exterior to the body, we suppose them also exterior to ourselves. The paper, on which I write at present, is beyond my hand. The table is beyond the paper. The walls of the chamber beyond the table. And in casting my eye towards the window, I perceive a great extent of fields and buildings beyond my chamber.

From all this it may be infered, that no other faculty is required, beside the senses, to convince us of the external existence of body. But to prevent this inference, we need only weigh the three following considerations. First, That, properly speaking, it is not our body we perceive, when we regard our limbs and members, but certain impressions, which enter by the senses; so that the ascribing a real and corporeal existence to these impressions, or to their objects, is an act of the mind as difficult to explain, as that which we examine at present. Secondly, Sounds, and tastes, and smelts, though commonly regarded by the mind as continued independent qualities, appear not to have any existence in extension, and consequently cannot appear to the senses as situated externally to the body. The reason, why we ascribe a place to them, shall be: considered afterwards.

Thirdly, Even our sight informs us not of distance or outness (so to speak) immediately and without a certain reasoning and experience, as is acknowledged by the most rational philosophers.

As to the independency of our perceptions on ourselves, this can never be an object of the senses; but any opinion we form concerning it, must be derived from experience and observation: And we shall see afterwards, that our conclusions from experience are far from being favourable to the doctrine of the independency of our perceptions. Mean while we may observe that when we talk of real distinct existences, we have commonly more in our eye their independency than external situation in place, and think an object has a sufficient reality, when its Being is uninterrupted, and independent of the incessant revolutions, which we are conscious of in ourselves.

Thus to resume what I have said concerning the senses; they give us no notion of continued existence, because they cannot operate beyond the extent, in which they really operate. They as little produce the opinion of a distinct existence, because they neither can offer it to the mind as represented, nor as original. To offer it as represented, they must present both an object and an image. To make it appear as original, they must convey a falshood; and this falshood must lie in the relations and situation: In order to which they must be able to compare the object with ourselves; and even in that case they do not, nor is it possible they should, deceive us. We may, therefore, conclude with certainty, that the opinion of a continued and of a distinct existence never arises from the senses.

To confirm this we may observe, that there are three different kinds of impressions conveyed by the senses. The first are those of the figure, bulk, motion and solidity of bodies. The second those of colours, tastes, smells, sounds, heat and cold. The third are the pains and pleasures, that arise from the application of objects to our bodies, as by the cutting of our flesh with steel, and such like. Both philosophers and the vulgar suppose the first of these to have a distinct continued existence.

The vulgar only regard the second as on the same footing. Both philosophers and the vulgar, again, esteem the third to be merely perceptions and consequently interrupted and dependent beings.

Now it is evident, that, whatever may be our philosophical opinion, colours, Sounds, heat and cold, as far as appears to the senses, exist after the same manner with motion and solidity, and that the difference we make betwixt them in this respect, arises not from the mere perception. So strong the prejudice for the distinct continued existence Of the former qualities, that when the contrary opinion is advanced by modern philosophers, people imagine they can almost refute it from their feeling and experience, and that their very senses contradict this philosophy. It is also evident, that colours, sounds, &c. are originally on the same footing with the pain that arises from steel, and pleasure that proceeds from a fire; and that the difference betwixt them is founded neither on perception nor reason, but on the imagination. For as they are confest to be, both of them, nothing but perceptions arising from the particular configurations and motions of the parts of body, wherein possibly can their difference consist?

Upon the whole, then, we may conclude, that as far as the senses are judges, all perceptions are the same in the manner of their existence.

We may also observe in this instance of sounds and colours, that we can attribute a distinct continued existence to objects without ever consulting REASON, or weighing our opinions by any philosophical principles. And indeed, whatever convincing arguments philosophers may fancy they can produce to establish the belief of objects independent of the mind, it is obvious these arguments are known but to very few, and that it is not by them, that children, peasants, and the greatest part of mankind are induced to attribute objects to some impressions, and deny them to others. Accordingly we find, that all the conclusions, which the vulgar form on this head, are directly contrary to those, which are confirmed by philosophy. For philosophy informs us, that every thing, which appears to the mind, is nothing but a perception, and is interrupted, and dependent on the mind: whereas the vulgar confound perceptions and objects, and attribute a distinct continued existence to the very things they feel or see. This sentiment, then, as it is entirely unreasonable, must proceed from some other faculty than the understanding.

To which we may add, that as long as we take our perceptions and objects to be the same, we can never infer the existence of the one from that of the other, nor form any argument from the relation of cause and effect; which is the only one that earl assure us of matter of fact. Even after we distinguish our perceptions from our objects, it will appear presently, that we are still incapable of reasoning from the existence of one to that of the other: So that upon the whole our reason neither does, nor is it possible it ever should, upon any supposition, give us an assurance of the continued and distinct existence of body. That opinion must be entirely owing to the IMAGINATION: which must now be the subject of our enquiry.

Since all impressions are internal and perishing existences, and appear as such, the notion of their distinct and continued existence must arise from a concurrence of some of their qualities with the qualities of the imagination, and since this notion does not extend to all of them, it must arise from certain qualities peculiar to some impressions. It will therefore be easy for us to discover these qualities by a comparison of the impressions, to which we attribute a distinct and continued existence, with those, which we regard as internal and perishing.

We may observe, then, that it is neither upon account of the involuntariness of certain impressions, as is commonly supposed, nor of their superior force and violence, that we attribute to them a reality, and continued existence, which we refuse to others, that are voluntary or feeble. For it is evident our pains and pleasures, our passions and affections, which we never suppose to have any existence beyond our perception, operate with greater violence, and are equally involuntary, as the impressions of figure and extension, colour and sound, which we suppose to be permanent beings. The heat of a fire, when moderate, is supposed to exist in the fire; but the pain, which it causes upon a near approach, is not taken to have any being, except in the perception.

These vulgar opinions, then, being rejected, we must search for some other hypothesis, by which we may discover those peculiar qualities in our impressions, which makes us attribute to them a distinct and continued existence.

After a little examination, we shall find, that all those objects, to which we attribute a continued existence, have a peculiar constancy, which distinguishes them from the impressions, whose existence depends upon our perception. Those mountains, and houses, and trees, which lie at present under my eye, have always appeared to me in the same order; and when I lose sight of them by shutting my eyes or turning my head, I soon after find them return upon me without the least alteration. My bed and table, my books and papers, present themselves in the same uniform manner, and change not upon account of any interruption in my seeing or perceivilng them. This is the case with all the impressions, whose objects are supposed to have an external existence; and is the case with no other impressions, whether gentle or violent, voluntary or involuntary.

This constancy, however, is not so perfect as not to admit of very considerable exceptions. Bodies often change their position and qualities, and after a little absence or interruption may become hardly knowable. But here it is observable, that even in these changes they preserve a coherence, and have a regular dependence on each other; which is the foundation of a kind of reasoning from causation, and produces the opinion of their continued existence. When I return to my chamber after an hour's absence, I find not my fire in the same situation, in which I left it: But then I am accustomed in other instances to see a like alteration produced in a like time, whether I am present or absent, near or remote. This coherence, therefore, in their changes is one of the characteristics of external objects, as well as their constancy.