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 can assure us of matter of fact. Even after we distinguish our perceptions from our objects, 'twill 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 inquiry.
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. 'Twill, 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 'tis 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 'tis 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 perceiving 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 'tis 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.
Having found that the opinion of the continued existence of body depends on the _coherence_ and _constancy_ of certain impressions, I now proceed to examine after what manner these qualities give rise to so extraordinary an opinion. To begin with the coherence; we may observe, that though those internal impressions, which we regard as fleeting and perishing, have also a certain coherence or regularity in their appearances, yet 'tis of somewhat a different nature from that which we discover in bodies. Our passions are found by experience to have a mutual connexion with, and dependence on each other; but on no occasion is it necessary to suppose that they have existed and operated, when they were not perceived, in order to preserve the same dependence and connexion, of which we have had experience. The case is not the same with relation to external objects. Those require a continued existence, or otherwise lose, in a great measure, the regularity of their operation. I am here seated in my chamber, with my face to the fire; and all the objects that strike my senses are contained in a few yards around me. My memory, indeed, informs me of the existence of many objects; but, then, this information extends not beyond their past existence, nor do either my senses or memory give any testimony to the continuance of their being. When, therefore, I am thus seated, and revolve over these thoughts, I hear on a sudden a noise as of a door turning upon its hinges; and a little after see a porter, who advances towards me. This gives occasion to many new reflections and reasonings. First, I never have observed that this noise could proceed from any thing but the motion of a door; and therefore conclude, that the present phenomenon is a contradiction to all past experience, unless the door, which I remember on t'other side the chamber, be still in being. Again, I have always found, that a human body was possessed of a quality which I call gravity, and which hinders it from mounting in the air, as this porter must have done to arrive at my chamber, unless the stairs I remember be not annihilated by my absence. But this is not all. I receive a letter, which, upon opening it, I perceive by the handwriting and subscription to have come from a friend, who says he is two hundred leagues distant. 'Tis evident I can never account for this phenomenon, conformable to my experience in other instances, without spreading out in my mind the whole sea and continent between us, and supposing the effects and continued existence of posts and ferries, according to my memory and observation. To consider these phenomena of the porter and letter in a certain light, they are contradictions to common experience, and may be regarded as objections to those maxims which we form concerning the connexions of causes and effects. I am accustomed to hear such a sound, and see such an object in motion at the same time. I have not received, in this particular instance, both these perceptions. These observations are contrary, unless I suppose that the door still remains, and that it was opened without my perceiving it: and this supposition, which was at first entirely arbitrary and hypothetical, acquires a force and evidence by its being the only one upon which I can reconcile these contradictions.
There is scarce a moment of my life, wherein there is not a similar instance presented to me, and I have not occasion to suppose the continued existence of objects, in order to connect their past and present appearances, and give them such an union with each other, as I have found, by experience, to be suitable to their particular natures and circumstances. Here, then, I am naturally led to regard the world as something real and durable, and as preserving its existence, even when it is no longer present to my perception.
But, though this conclusion, from the coherence of appearances, may seem to be of the same nature with our reasonings concerning causes and effects, as being derived from custom, and regulated by past experience, we shall find, upon examination, that they are at the bottom considerably different from each other, and that this inference arises from the understanding and from custom, in an indirect and oblique manner. For 'twill readily be allowed, that since nothing is ever really present to the mind, besides its own perceptions, 'tis not only impossible that any habit should ever be acquired otherwise than by the regular succession of these perceptions, but also that any habit should ever exceed that degree of regularity. Any degree, therefore, of regularity in our perceptions, can never be a foundation for us to infer a greater degree of regularity in some objects which are not perceived, since this supposes a contradiction, viz. a habit acquired by what was never present to the mind. But, 'tis evident that, whenever we infer the continued existence of the objects of sense from their coherence, and the frequency of their union, 'tis in order to bestow on the objects a greater regularity than what is observed in our mere perceptions. We remark a connexion betwixt two kinds of objects in their past appearance to the senses, but are not able to observe this connexion to be perfectly constant, since the turning about of our head, or the shutting of our eyes, is able to break it. What, then, do we suppose in this case, but that these objects still continue their usual connexion, notwithstanding their apparent interruption, and that the irregular appearances are joined by something of which we are insensible? But as all reasoning concerning matters of fact arises only from custom, and custom can only be the effect of repeated perceptions, the extending of custom and reasoning beyond the perceptions can never be the direct and natural effect of the constant repetition and connexion, but must arise from the cooperation of some other principles.
I have already observed,[3] in examining the foundation of mathematics, that the imagination, when set into any train of thinking, is apt to continue even when its object fails it, and, like a galley put in motion by the oars, carries on its course without any new impulse. This I have assigned for the reason, why, after considering several loose standards of equality, and correcting them by each other, we proceed to imagine so correct and exact a standard of that relation as is not liable to the least error or variation. The same principle makes us easily entertain this opinion of the continued existence of body.
Objects have a certain coherence even as they appear to our senses; but this coherence is much greater and more uniform if we suppose the objects to have a continued existence; and as the mind is once in the train of observing an uniformity among objects, it naturally continues till it renders the uniformity as complete as possible. The simple supposition of their continued existence suffices for this purpose, and gives us a notion of a much greater regularity among objects, than what they have when we look no farther than our senses.
But whatever force we may ascribe to this principle, I am afraid 'tis too weak to support alone so vast an edifice as is that of the continued existence of all external bodies; and that we must join the _constancy_ of their appearance to the _coherence_, in order to give a satisfactory account of that opinion. As the explication of this will lead me into a considerable compass of very profound reasoning, I think it proper, in order to avoid confusion, to give a short sketch or abridgment of my system, and afterwards draw out all its parts in their full compass. This inference from the constancy of our perceptions, like the precedent from their coherence, gives rise to the opinion of the _continued_ existence of body, which is prior to that of its _distinct_ existence, and produces that latter principle.
When we have been accustomed to observe a constancy in certain impressions, and have found that the perception of the sun or ocean, for instance, returns upon us, after an absence or annihilation, with like parts and in a like order as at its first appearance, we are not apt to regard these interrupted perceptions as different (which they really are), but on the contrary consider them as individually the same, upon account of their resemblance. But as this interruption of their existence is contrary to their perfect identity, and makes us regard the first impression as annihilated, and the second as newly created, we find ourselves somewhat at a loss, and are involved in a kind of contradiction. In order to free ourselves from this difficulty, we disguise, as much as possible, the interruption, or rather remove it entirely, by supposing that these interrupted perceptions are connected by a real existence, of which we are insensible. This supposition, or idea of continued existence, acquires a force and vivacity from the memory of these broken impressions, and from that propensity which they give us to suppose them the same; and according to the precedent reasoning, the very essence of belief consists in the force and vivacity of the conception.
In order to justify this system, there are four things requisite.
_First_, to explain the _principium individuations_, or principle of identity. _Secondly_, give a reason why the resemblance of our broken and interrupted perceptions induces us to attribute an identity to them. _Thirdly_, account for that propensity, which this allusion gives, to unite these broken appearances by a continued existence.
_Fourthly_, and lastly, explain that force and vivacity of conception which arises from the propensity.
First, as to the principle of individuation, we may observe, that the view of any one object is not sufficient to convey the idea of identity. For in that proposition, _an object is the same with itself_, if the idea expressed by the word _object_ were no ways distinguished from that meant by _itself_; we really should mean nothing, nor would the proposition contain a predicate and a subject, which, however, are implied in this affirmation. One single object conveys the idea of unity, not that of identity.
On the other hand, a multiplicity of objects can never convey this idea, however resembling they may be supposed. The mind always pronounces the one not to be the other, and considers them as forming two, three, or any determinate number of objects, whose existences are entirely distinct and independent.
Since then both number and unity are incompatible with the relation of identity, it must lie in something that is neither of them. But to tell the truth, at first sight this seems utterly impossible. Betwixt unity and number there can be no medium; no more than betwixt existence and non-existence. After one object is supposed to exist, we must either suppose another also to exist; in which case we have the idea of number: or we must suppose it not to exist; in which case the first object remains at unity.
To remove this difficulty, let us have recourse to the idea of time or duration. I have already observed,[4] that time, in a strict sense, implies succession, and that, when we apply its idea to any unchangeable object, 'tis only by a fiction of the imagination by which the unchangeable object is supposed to participate of the changes of the co-existent objects, and in particular of that of our perceptions. This fiction of the imagination almost universally takes place; and 'tis by means of it that a single object, placed before us, and surveyed for any time without our discovering in it any interruption or variation, is able to give us a notion of identity.
For when we consider any two points of this time, we may place them in different lights: we may either survey them at the very same instant; in which case they give us the idea of number, both by themselves and by the object; which must be multiplied in order to be conceived at once, as existent in these two different points of time: or, on the other hand, we may trace the succession of time by a like succession of ideas, and conceiving first one moment, along with the object then existent, imagine afterwards a change in the time without any _variation_ or _interruption_ in the object; in which case it gives us the idea of unity. Here then is an idea, which is a medium betwixt unity and number; or, more properly speaking, is either of them, according to the view in which we take it: and this idea we call that of identity. We cannot, in any propriety of speech, say that an object is the same with itself, unless we mean that the object existent at one time is the same with itself existent at another. By this means we make a difference betwixt the idea meant by the word _object_, and that meant by _itself_, without going the length of number, and at the same time without restraining ourselves to a strict and absolute unity.
Thus the principle of individuation is nothing but the _invariableness_ and _uninterruptedness_ of any object, through a supposed variation of time, by which the mind can trace it in the different periods of its existence, without any break of the view, and without being obliged to form the idea of multiplicity or number.
I now proceed to explain the _second_ part of my system, and show why the constancy of our perceptions makes us ascribe to them a perfect numerical identity, though there be very long intervals betwixt their appearance, and they have only one of the essential qualities of identity, viz. _invariableness_. That I may avoid all ambiguity and confusion on this head, I shall observe, that I here account for the opinions and belief of the vulgar with regard to the existence of body; and therefore must entirely conform myself to their manner of thinking and of expressing themselves. Now, we have already observed, that however philosophers may distinguish betwixt the objects and perceptions of the senses; which they suppose co-existent and resembling; yet this is a distinction which is not comprehended by the generality of mankind, who, as they perceive only one being, can never assent to the opinion of a double existence and representation.
Those very sensations which enter by the eye or ear are with them the true objects, nor can they readily conceive that this pen or paper, which is immediately perceived, represents another which is different from, but resembling it. In order, therefore, to accommodate myself to their notions, I shall at first suppose that there is only a single existence, which I shall call indifferently _object_ or _perception_, according as it shall seem best to suit my purpose, understanding by both of them what any common man means by a hat, or shoe, or stone, or any other impression conveyed to him by his senses. I shall be sure to give warning when I return to a more philosophical way of speaking and thinking.
To enter therefore upon the question concerning the source of the error and deception with regard to identity, when we attribute it to our resembling perceptions, notwithstanding their interruption, I must here recal an observation which I have already proved and explained.[5] Nothing is more apt to make us mistake one idea for another, than any relation betwixt them, which associates them together in the imagination, and makes it pass with facility from one to the other. Of all relations, that of resemblance is in this respect the most efficacious; and that because it not only causes an association of ideas, but also of dispositions, and makes us conceive the one idea by an act or operation of the mind, similar to that by which we conceive the other. This circumstance I have observed to be of great moment; and we may establish it for a general rule, that whatever ideas place the mind in the same disposition or in similar ones, are very apt to be confounded. The mind readily passes from one to the other, and perceives not the change without a strict attention, of which, generally speaking, 'tis wholly incapable.
In order to apply this general maxim, we must first examine the disposition of the mind in viewing any object which preserves a perfect identity, and then find some other object that is confounded with it, by causing a similar disposition. When we fix our thought on any object, and suppose it to continue the same for some time, 'tis evident we suppose the change to lie only in the time, and never exert ourselves to produce any new image or idea of the object. The faculties of the mind repose themselves in a manner, and take no more exercise than what is necessary to continue that idea of which we were formerly possessed, and which subsists without variation or interruption. The passage from one moment to another is scarce felt, and distinguishes not itself by a different perception or idea, which may require a different direction of the spirits, in order to its conception.
Now, what other objects, beside identical ones, are capable of placing the mind in the same disposition, when it considers them, and of causing the same uninterrupted passage of the imagination from one idea to another? This question is of the last importance. For if we can find any such objects, we may certainly conclude, from the foregoing principle, that they are very naturally confounded with identical ones, and are taken for them in most of our reasonings. But though this question be very important, 'tis not very difficult nor doubtful.
For I immediately reply, that a succession of related objects places the mind in this disposition, and is considered with the same smooth and uninterrupted progress of the imagination, as attends the view of the same invariable object. The very nature and essence of relation is to connect our ideas with each other, and upon the appearance of one, to facilitate the transition to its correlative. The passage betwixt related ideas, is therefore so smooth and easy, that it produces little alteration on the mind, and seems like the continuation of the same action; and as the continuation of the same action is an effect of the continued view of the same object, 'tis for this reason we attribute sameness to every succession of related objects. The thought slides along the succession with equal facility, as if it considered only one object; and therefore confounds the succession with the identity.
We shall afterwards see many instances of this tendency of relation to make us ascribe an _identity_ to _different_ objects; but shall here confine ourselves to the present subject. We find by experience, that there is such a _constancy_ in almost all the impressions of the senses, that their interruption produces no alteration on them, and hinders them not from returning the same in appearance and in situation as at their first existence. I survey the furniture of my chamber; I shut my eyes, and afterwards open them; and find the new perceptions to resemble perfectly those which formerly struck my senses. This resemblance is observed in a thousand instances, and naturally connects together our ideas of these interrupted perceptions by the strongest relation, and conveys the mind with an easy transition from one to another. An easy transition or passage of the imagination, along the ideas of these different and interrupted perceptions, is almost the same disposition of mind with that in which we consider one constant and uninterrupted perception. 'Tis therefore very natural for us to mistake the one for the other.[6] The persons who entertain this opinion concerning the identity of our resembling perceptions, are in general all the unthinking and unphilosophical part of mankind, (that is, all of us at one time or other), and, consequently, such as suppose their perceptions to be their only objects, and never think of a double existence internal and external, representing and represented. The very image which is present to the senses is with us the real body; and 'tis to these interrupted images we ascribe a perfect identity. But as the interruption of the appearance seems contrary to the identity, and naturally leads us to regard these resembling perceptions as different from each other, we here find ourselves at a loss how to reconcile such opposite opinions. The smooth passage of the imagination along the ideas of the resembling perceptions makes us ascribe to them a perfect identity. The interrupted manner of their appearance makes us consider them as so many resembling, but still distinct beings, which appear after certain intervals. The perplexity arising from this contradiction produces a propension to unite these broken appearances by the fiction of a continued existence, which is the _third_ part of that hypothesis I proposed to explain.
Nothing is more certain from experience than that any contradiction either to the sentiments or passions gives a sensible uneasiness, whether it proceeds from without or from within; from the opposition of external objects, or from the combat of internal principles. On the contrary, whatever strikes in with the natural propensities, and either externally forwards their satisfaction, or internally concurs with their movements, is sure to give a sensible pleasure. Now, there being here an opposition betwixt the notion of the identity of resembling perceptions, and the interruption of their appearance, the mind must be uneasy in that situation, and will naturally seek relief from the uneasiness. Since the uneasiness arises from the opposition of two contrary principles, it must look for relief by sacrificing the one to the other. But as the smooth passage of our thought along our resembling perceptions makes us ascribe to them an identity, we can never, without reluctance, yield up that opinion. We must therefore turn to the other side, and suppose that our perceptions are no longer interrupted, but preserve a continued as well as an invariable existence, and are by that means entirely the same. But here the interruptions in the appearance of these perceptions are so long and frequent, that 'tis impossible to overlook them; and as the _appearance_ of a perception in the mind and its _existence_ seem at first sight entirely the same, it may be doubted whether we can ever assent to so palpable a contradiction, and suppose a perception to exist without being present to the mind. In order to clear up this matter, and learn how the interruption in the appearance of a perception implies not necessarily an interruption in its existence, 'twill be proper to touch upon some principles which we shall have occasion to explain more fully afterwards.[7] We may begin with observing, that the difficulty in the present case is not concerning the matter of fact, or whether the mind forms such a conclusion concerning the continued existence of its perceptions, but only concerning the manner in which the conclusion is formed, and principles from which it is derived. 'Tis certain that almost all mankind, and even philosophers themselves, for the greatest part of their lives, take their perceptions to be their only objects, and suppose that the very being which is intimately present to the mind, is the real body or material existence. 'Tis also certain that this very perception or object is supposed to have a continued uninterrupted being, and neither to be annihilated by our absence, nor to be brought into existence by our presence. When we are absent from it, we say it still exists, but that we do not feel, we do not see it. When we are present, we say we feel or see it. Here then may arise two questions; _first_, how we can satisfy ourselves in supposing a perception to be absent from the mind without being annihilated. _Secondly_, after what manner we conceive an object to become present to the mind, without some new creation of a perception or image; and what we mean by this As to the first question, we may observe, that what we call a _mind_, is nothing but a heap or collection of different perceptions, united together by certain relations, and supposed, though falsely, to be endowed with a perfect simplicity and identity. Now, as every perception is distinguishable from another, and may be considered as separately existent; it evidently follows, that there is no absurdity in separating any particular perception from the mind; that is, in breaking off all its relations with that connected mass of perceptions which constitute a thinking being.
The same reasoning affords us an answer to the second question. If the name of _perception_ renders not this separation from a mind absurd and contradictory, the name of _object_, standing for the same thing, can never render their conjunction impossible. External objects are seen and felt, and become present to the mind; that is, they acquire such a relation to a connected heap of perceptions as to influence them very considerably in augmenting their number by present reflections and passions, and in storing the memory with ideas. The same continued and uninterrupted being may, therefore, be sometimes present to the mind and sometimes absent from it without any real or essential change in the being itself. An interrupted appearance to the senses implies not necessarily an interruption in the existence. The supposition of the continued existence of sensible objects or perceptions involves no contradiction. We may easily indulge our inclination to that supposition. When the exact resemblance of our perceptions makes us ascribe to them an identity, we may remove the seeming interruption by feigning a continued being, which may fill those intervals, and preserve a perfect and entire identity to our perceptions.
But as we here not only _feign_ but _believe_ this continued existence, the question is, _from whence arises such a belief_? and this question leads us to the _fourth_ member of this system. It has been proved already, that belief, in general, consists in nothing but the vivacity of an idea; and that an idea may acquire this vivacity by its relation to some present impression. Impressions are naturally the most vivid perceptions of the mind; and this quality is in part conveyed by the relation to every connected idea. The relation causes a smooth passage from the impression to the idea, and even gives a propensity to that passage. The mind falls so easily from the one perception to the other, that it scarce perceives the change, but retains in the second a considerable share of the vivacity of the first. It is excited by the lively impression, and this vivacity is conveyed to the related idea, without any great diminution in the passage, by reason of the smooth transition and the propensity of the imagination.
But suppose that this propensity arises from some other principle, besides that of relation; 'tis evident, it must still have the same effect, and convey the vivacity from the impression to the idea. Now, this is exactly the present case. Our memory presents us with a vast number of instances of perceptions perfectly resembling each other, that return at different distances of time, and after considerable interruptions. This resemblance gives us a propension to consider these interrupted perceptions as the same; and also a propension to connect them by a continued existence, in order to justify this identity, and avoid the contradiction in which the interrupted appearance of these perceptions seems necessarily to involve us. Here then we have a propensity to feign the continued existence of all sensible objects; and as this propensity arises from some lively impressions of the memory, it bestows a vivacity on that fiction; or, in other words, makes us believe the continued existence of body. If, sometimes we ascribe a continued existence to objects, which are perfectly new to us, and of whose constancy and coherence we have no experience, 'tis because the manner, in which they present themselves to our senses, resembles that of constant and coherent objects; and this resemblance is a source of reasoning and analogy, and leads us to attribute the same qualities to the similar objects.
I believe an intelligent reader will find less difficulty to assent to this system, than to comprehend it fully and distinctly, and will allow, after a little reflection, that every part carries its own proof along with it. 'Tis indeed evident, that as the vulgar _suppose_ their perceptions to be their only objects, and at the same time _believe_ the continued existence of matter, we must account for the origin of the belief upon that supposition. Now, upon that supposition, 'tis a false opinion that any of our objects, or perceptions, are identically the same after an interruption; and consequently the opinion of their identity can never arise from reason, but must arise from the imagination. The imagination is seduced into such an opinion only by means of the resemblance of certain perceptions; since we find they are only our resembling perceptions, which we have a propension to suppose the same. This propension to bestow an identity on our resembling perceptions, produces the fiction of a continued existence; since that fiction, as well as the identity, is really false, as is acknowledged by all philosophers, and has no other effect than to remedy the interruption of our perceptions, which is the only circumstance that is contrary to their identity. In the last place, this propension causes belief by means of the present impressions of the memory; since, without the remembrance of former sensations, 'tis plain we never should have any belief of the continued existence of body. Thus, in examining all these parts, we find that each of them is supported by the strongest proofs; and that all of them together form a consistent system, which is perfectly convincing. A strong propensity or inclination alone, without any present impression, will sometimes cause a belief or opinion. How much more when aided by that circumstance!
But though we are led after this manner, by the natural propensity of the imagination, to ascribe a continued existence to those sensible objects or perceptions, which we find to resemble each other in their interrupted appearance; yet a very little reflection and philosophy is sufficient to make us perceive the fallacy of that opinion. I have already observed, that there is an intimate connexion betwixt those two principles, of a _continued_ and of a _distinct_ or _independent_ existence, and that we no sooner establish the one than the other follows, as a necessary consequence. 'Tis the opinion of a continued existence, which first takes place, and without much study or reflection draws the other along with it, wherever the mind follows