There is no foundation for any conclusion a priori, either concerning the operations or duration of any object, of which it is possible for the human mind to form a conception.  Any object may be imagined to become entirely inactive, or to be annihilated in a moment; and it is an evident principle, that whatever we can imagine, is possible.  Now this is no more true of matter, than of spirit; of an extended compounded substance, than of a simple and unextended.  In both cases the metaphysical arguments for the immortality of the soul are equally inconclusive:  and in both cases the moral arguments and those derived from the analogy of nature are equally strong and convincing.  If my philosophy, therefore, makes no addition to the arguments for religion, I have at least the satisfaction to think it takes nothing from them, but that every thing remains precisely as before.

SECT.  VI.  OF PERSONAL IDENTITY

There are some philosophers. who imagine we are every moment intimately conscious of what we call our self; that we feel its existence and its continuance in existence; and are certain, beyond the evidence of a demonstration, both o its perfect identity and simplicity.  The strongest sensation, the most violent passion, say they, instead of distracting us from this view, only fix it the more intensely, and make us consider their influence on self either by their pain or pleasure.  To attempt a farther proof of this were to weaken its evidence; since no proof can be derived from any fact, of which we are so intimately conscious; nor is there any thing, of which we can be certain, if we doubt of this.

Unluckily all these positive assertions are contrary to that very experience, which is pleaded for them, nor have we any idea of self, after the manner it is here explained.  For from what impression coued this idea be derived?  This question it is impossible to answer without a manifest contradiction and absurdity; and yet it is a question, which must necessarily be answered, if we would have the idea of self pass for clear and intelligible, It must be some one impression, that gives rise to every real idea.  But self or person is not any one impression, but that to which our several impressions and ideas are supposed to have a reference.  If any impression gives rise to the idea of self, that impression must continue invariably the same, through the whole course of our lives; since self is supposed to exist after that manner.  But there is no impression constant and invariable.  Pain and pleasure, grief and joy, passions and sensations succeed each other, and never all exist at the same time.  It cannot, therefore, be from any of these impressions, or from any other, that the idea of self is derived; and consequently there is no such idea.