the centre of it. I see an object in motion on the top of yonder hill; I cannot discern whether it be a man, or a horse, or both; I therefore exert no belief in regard to the class or species of objects to which it belongs, but I believe with as much assurance that it exists, as if I saw it distinctly in all its parts and dimensions. We have never any doubt of the existence of an object so long as we are sure that we perceive it by our senses, whether the perception be strong or weak, distinct or confused; but whenever we begin to doubt, whether the object be perceived by our senses, or whether we only imagine that we perceive it, then we likewise begin to doubt of its existence.

These observations are applicable to memory. I saw a certain object some years ago; my remembrance of it is less distinct now than it was the day after I saw it; but I believe the evidence of my memory as much at present as I did then, in regard to all the parts of it which I now am conscious that I remember. Let a past event be ever so remote in time, if I am conscious that I remember it, I still believe, with equal assurance, that this event did once take place. For what is memory, but a consciousness of our haying formerly done or perceived something? And if it be true, that something is perceived or done at this present moment, it will always be true, that at this moment that thing was perceived or done, The evidence of memory does not decay in proportion as the ideas of memory becomes less lively; as long as we are conscious that we remember, as long will the evidence attending that remembrance produce absolute certainty; and absolute certainty admits not of degrees. Indeed, as was already observed, when remembrance becomes so obscure, that we are at a loss

to determine whether we remember, or only imagine an event, in this case belief will be suspended till we become certain whether we remember or not; whenever we become certain that we do remember, conviction instantly arises.

Some have supposed that the evidence of memory is liable to become uncertain, because we are not well enough acquainted with the difference between memory and imagination, to be able at all times to determine, whether the one or the other be exerted in regard to the events or facts we may have occasion to contemplate. "You say, that while you only ima66 gine an event, you neither believe nor disbelieve the "existence or reality of it: but that as soon as you "become conscious that you remember it, you instantly believe it to have been real. You must "then know with certainty the difference between

memory and imagination, and be able to tell by "what marks you distinguish the operations of the "former from those of the latter. If you cannot do "this, you may mistake the one for the other, and "think that you imagine when you really remember, "and that you remember when you only imagine. "That belief, therefore, must be very precarious and "uncertain, which is built upon the evidence of memory, since this evidence is so apt to be confound"ed with the visionary exhibitions of imagination, "which, by your own acknowledgment, can never "constitute a foundation for true rational belief." This is an objection, according to the metaphysical mode, which, without consulting experience, is satisfied if a few plausible words can be put together in the form of an argument: but this objection will have no credit with those who acknowledge ultimate instinc

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tive principles of conviction, and who have more faith in their own feelings than in the subtleties of logic.

It is certain the vulgar are not able to give a satisfactory account of the difference between memory and imagination; even philosophers have not always succeeded in their attempts to illustrate this point. Mr HUME tells us, that ideas of memory are distinguished from those of imagination by the superior vivacity of the former *. This may sometimes, but cannot always be true for ideas of imagination are often mistaken for objects of sense; ideas of memory never: The former, therefore, must often be more lively than the latter; for, according to Mr HUME's own account, all ideas are weaker than impressions, or informations of sense † Dreaming persons, lunatics, stage-players, enthusiasts, and all who are agitated by fear, or other violent passions, are apt to mistake ideas of ima gination for real things, and the perception of those ideas for real sensation. And the same thing is often experienced by persons of strong fancy, and great sen→ sibility of temper, at a time when they are not troubled with any fits of irrationality or violent passion.

But whatever difficulty we may find in defining or describing memory, so as to distinguish it from ima gination, we are never at any loss about our own meaning, when we speak of remembering and of ima gining. We all know what it is to remember, and what it is to imagine; a retrospect to former experience always attends the exertions of memory; but those of imagination are not attended with any retrospect. "I remember to have seen a lion, and I can imagine an elephant or centaur, which I have never seen:"-Every body who uses these words * Treatise of Human Nature, vol. 1. p. 153.

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+ Ibid. p. 41.

such

knows very well what they mean, whether he be able to explain his meaning by other words or not. The truth is, that when we remember, we generally know that we remember; when we imagine, we generally know that we imagine *: such is our constitution. We therefore do not suppose the evidence of memory uncertain, notwithstanding that we may be at a loss to explain the difference between that faculty and imagination; the difference is perfectly known to every man by experience, though perhaps no man can fully express it in words. There are many things very familiar to us, which we have no words to express. I cannot describe or define, either a red colour, which I know to be a simple object, or a white colour, which I know to be a composition of seven colours: but will any one hence infer, that I am ignorant of their difference, so as not to know, when I look on ermine, whether it be white or red? Let it not then be said, that because we cannot define memory and imagination, therefore we are ignorant of their difference every person of a sound mind, knows their difference, and can with certainty determine, when it is that he exerts the one, and when it is that he exerts the other.

SECT. V.

Of Reasoning from the Effect to the Cause. LEFT my chamber an hour ago, and now at my return find a book on the table, the size, and binding, and contents of which are so remarkable, that

* In dreams, indeed, this is not the case; but the delusions of dreaming, notwithstanding our frequent experience of them, are never supposed to effect in the least degree either the veracity of our faculties, or the certainty of our knowledge. See below, Part II. Chap. 2. Sect. 2.

I am certain it was not here when I went out; and that I never saw it before. I ask, who brought this book; and am told, that no body has entered my apartment since I left it. That, say I, is impossible. I make a more particular inquiry; and a servant, in whose veracity I can confide, assures me, that he has had his eye on my chamber-door the whole day, and that no person has entered it but myself only. Then, say I, the person who brought this book must have come in by the window or the chimney; for it is impossible that this book could have come hither of itself. The. servant bids me remember, that my chimney is too narrow to admit any human creature, and that the window is secured on the inside in such a manner that it cannot be opened from without., I examine the walls; it is evident no breach has been made: and there is but one door to the apartment. What shall I think? If the servant's report be true, and if the book have not been brought by any visible agent, it must have come in a miraculous manner, by the interposition of some visible cause; for still I must repeat, that without some cause it could not possibly. bave come hither.

Let the reader consider the case, and deliberate with himself whether I think irrationally on this occasion, or express myself too strongly, when I speak of the impossibility of a book appearing in my chamber without some cause of its appearance, either visible or invisible. I would not willingly refer such a phenomenon to a miracle; but still a miracle is possible; whereas it is absolutely impossible that this could have happened without a cause; at least it seems to me to be as real an impossibility, as that a part should be greater than the whole, or that things