The subject, then, of our present enquiry is concerning the causes which induce us to believe in the existence of body:  And my reasonings on this head I shall begin with a distinction, which at first sight may seem superfluous, but which will contribute very much to the perfect understanding of what follows.  We ought to examine apart those two questions, which are commonly confounded together, viz.  Why we attribute a continued existence to objects, even when they are not present to the senses; and why we suppose them to have an existence distinct from the mind and perception.  Under this last head I comprehend their situation as well as relations, their external position as well as the independence of their existence and operation.  These two questions concerning the continued and distinct existence of body are intimately connected together.  For if the objects of our senses continue to exist, even when they are not perceived, their existence is of course independent of and distinct from the perception:  and vice versa, if their existence be independent of the perception and distinct from it, they must continue to exist, even though they be not perceived.  But though the decision of the one question decides the other; yet that we may the more easily discover the principles of human nature, from whence the decision arises, we shall carry along with us this distinction, and shall consider, whether it be the senses, reason, or the imagination, that produces the opinion of a continued or of a distinct existence.  These are the only questions, that are intelligible on the present subject.  For as to the notion of external existence, when taken for something specially different from our perceptions [Part.  II.  Sect. 6.], we have already shewn its absurdity.

To begin with the senses, it is evident these faculties are incapable of giving rise to the notion of the continued existence of their objects, after they no longer appear to the senses.  For that is a contradiction in terms, and suppose that the senses continue to operate, even after they have ceased all manner of operation.  These faculties, therefore, if they have any influence in the present case, must produce the opinion of a distinct, not of a continued existence; and in order to that, must present their impressions either as images and representations, or as these very distinct and external existences.

That our senses offer not their impressions as the images of something distinct, or independent, and external, is evident; because they convey to us nothing but a single perception, and never give us the least intimation of any thing beyond.  A single perception can never produce the idea of a double existence, but by some inference either of the reason or imagination.  When the mind looks farther than what immediately appears to it, its conclusions can never be put to the account of the senses; and it certainly looks farther, when from a single perception it infers a double existence, and supposes the relations of resemblance and causation betwixt them.