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 its first and most natural tendency. But when we compare experiments, and reason a little upon them, we quickly perceive, that the doctrine of the independent existence of our sensible perceptions is contrary to the plainest experience. This leads us backward upon our footsteps to perceive our error in attributing a continued existence to our perceptions, and is the origin of many very curious opinions, which we shall here endeavour to account for.
'Twill first be proper to observe a few of those experiments, which convince us, that our perceptions are not possessed of any independent existence. When we press one eye with a finger, we immediately perceive all the objects to become double, and one half of them to be removed from their common and natural position. But as we do not attribute a continued existence to both these perceptions, and as they are both of the same nature, we clearly perceive, that all our perceptions are dependent on our organs, and the disposition of our nerves and animal spirits. This opinion is confirmed by the seeming increase and diminution of objects according to their distance; by the apparent alterations in their figure; by the changes in their colour and other qualities, from our sickness and distempers, and by an infinite number of other experiments of the same kind; from all which we learn, that our sensible perceptions are not possessed of any distinct or independent existence.
The natural consequence of this reasoning should be, that our perceptions have no more a continued than an independent existence; and, indeed, philosophers have so far run into this opinion, that they change their system, and distinguish (as we shall do for the future) betwixt perceptions and objects, of which the former are supposed to be interrupted and perishing, and different at every different return; the latter to be uninterrupted, and to preserve a continued existence and identity. But however philosophical this new system may be esteemed, I assert that 'tis only a palliative remedy, and that it contains all the difficulties of the vulgar system, with some others that are peculiar to itself. There are no principles either of the understanding or fancy, which lead us directly to embrace this opinion of the double existence of perceptions and objects, nor can we arrive at it but by passing through the common hypothesis of the identity and continuance of our interrupted perceptions. Were we not first persuaded that our perceptions are our only objects, and continue to exist even when they no longer make their appearance to the senses, we should never be led to think that our perceptions and objects are different, and that our objects alone preserve a continued existence. "The latter hypothesis has no primary recommendation either to reason or the imagination, but acquires all its influence on the imagination from the former." This proposition contains two parts, which we shall endeavour to prove as distinctly and clearly as such abstruse subjects will permit.
As to the first part of the proposition, that this philosophical hypothesis has no primary recommendation, either to reason or the imagination, we may soon satisfy ourselves with regard to reason, by the following reflections. The only existences, of which we are certain, are perceptions, which, being immediately present to us by consciousness, command our strongest assent, and are the first foundation of all our conclusions. The only conclusion we can draw from the existence of one thing to that of another, is by means of the relation of cause and effect, which shows, that there is a connexion betwixt them, and that the existence of one is dependent on that of the other. The idea of this relation is derived from past experience, by which we find, that two beings are constantly conjoined together, and are always present at once to the mind. But as no beings are ever present to the mind but perceptions, it follows, that we may observe a conjunction or a relation of cause and effect between different perceptions, but can never observe it between perceptions and objects. 'Tis impossible, therefore, that from the existence or any of the qualities of the former, we can ever form any conclusion concerning the existence of the latter, or ever satisfy our reason in this particular.
'Tis no less certain, that this philosophical system has no primary recommendation to the imagination, and that that faculty would never, of itself, and by its original tendency, have fallen upon such a principle. I confess it will be somewhat difficult to prove this to the full satisfaction of the reader; because it implies a negative, which in many cases will not admit of any positive proof. If any one would take the pains to examine this question, and would invent a system, to account for the direct origin of this opinion from the imagination, we should be able, by the examination of that system, to pronounce a certain judgment in the present subject. Let it be taken for granted, that our perceptions are broken and interrupted, and, however like, are still different from each other; and let any one, upon this supposition, show why the fancy, directly and immediately, proceeds to the belief of another existence, resembling these perceptions in their nature, but yet continued, and uninterrupted, and identical; and after he has done this to my satisfaction, I promise to renounce my present opinion. Meanwhile I cannot forbear concluding, from the very abstractedness and difficulty of the first supposition, that 'tis an improper subject for the fancy to work upon. Whoever would explain the origin of the common opinion concerning the continued and distinct existence of body, must take the mind in its common situation, and must proceed upon the supposition, that our perceptions are our only objects, and continue to exist even when they are not perceived. Though this opinion be false, 'tis the most natural of any, and has alone any primary recommendation to the fancy.
As to the second part of the proposition, that the philosophical system acquires all its influence on the imagination from the vulgar one; we may observe, that this is a natural and unavoidable consequence of the foregoing conclusion, that it has no primary recommendation to reason or the imagination. For as the philosophical system is found by experience to take hold of many minds, and, in particular, of all those who reflect ever so little on this subject, it must derive all its authority from the vulgar system, since it has no original authority of its own. The manner in which these two systems, though directly contrary, are connected together, may be explained as follows.
The imagination naturally runs on in this train of thinking. Our perceptions are our only objects: resembling perceptions are the same, however broken or uninterrupted in their appearance: this appearing interruption is contrary to the identity: the interruption consequently extends not beyond the appearance, and the perception or object really continues to exist, even when absent from us: our sensible perceptions have, therefore, a continued and uninterrupted existence. But as a little reflection destroys this conclusion, that our perceptions have a continued existence, by showing that they have a dependent one, 'twould naturally be expected, that we must altogether reject the opinion, that there is such a thing in nature as a continued existence, which is preserved even when it no longer appears to the senses. The case, however, is otherwise. Philosophers are so far from rejecting the opinion of a continued existence upon rejecting that of the independence and continuance of our sensible perceptions, that though all sects agree in the latter sentiment, the former, which is in a manner its necessary consequence, has been peculiar to a few extravagant sceptics; who, after all, maintained that opinion in words only, and were never able to bring themselves sincerely to believe it.