Page:Treatise of Human Nature (1888).djvu/219

199 that of the continu'd existence of all external bodies; and we must join the constancy of their appearance to the coherence, in order to give a satisfactory account of 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 continu'd existence of body, which is prior to that of its distinct existence, and produces that latter principle.

When we have been accustom'd 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 involv'd 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 continu'd 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 individuationis,