| 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 involved 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 continued 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, or principle of identity. |
| Secondly, Give a reason, why the resemblance of our broken and interrupted perceptions induces us to attribute an identity to them. |
| Thirdly, Account for that propensity, which this illusion gives, to unite these broken appearances by a continued existence. |
| Fourthly and lastly, Explain that force and vivacity of conception, which arises from the propensity. |
| First, As to the principle of individuation; we may observe, that the view of any one object is not sufficient to convey the idea of identity. |
| For in that proposition, an object is the same with itself, if the idea expressed by the word, object, were no ways distinguished from that meant by itself; we really should mean nothing, nor would the proposition contain a predicate and a subject, which however are implyed in this affirmation. |
| One single object conveys the idea of unity, not that of identity. |
| On the other hand, a multiplicity of objects can never convey this idea, however resembling they may be supposed. |
| The mind always pronounces the one not to be the other, and considers them as forming two, three, or any determinate number of objects, whose existences are entirely distinct and independent. |
| Since then both number and unity are incompatible with the relation of identity, it must lie in something that is neither of them. |
| But to tell the truth, at first sight this seems utterly impossible. |
| Betwixt unity and number there can be no medium; no more than betwixt existence and nonexistence. |
| After one object is supposed to exist, we must either suppose another also to exist; in which case we have the idea of number: Or we must suppose it not to exist; in which case the first object remains at unity. |
| To remove this difficulty, let us have recourse to the idea of time or duration. |
| I have already observd [Part II, SECT. 5.], that time, in a strict sense, implies succession, and that when we apply its idea to any unchangeable object, it is only by a fiction of the imagination, by which the unchangeable object is supposd to participate of the changes of the co-existent objects, and in particular of that of our perceptions. |
| This fiction of the imagination almost universally takes place; and it is by means of it, that a single object, placd before us, and surveyd for any time without our discovering in it any interruption or variation, is able to give us a notion of identity. |
| For when we consider any two points of this time, we may place them in different lights: We may either survey them at the very same instant; in which case they give us the idea of number, both by themselves and by the object; which must be multiplyd, in order to be conceivd at once, as existent in these two different points of time: Or on the other hand, we may trace the succession of time by a like succession of ideas, and conceiving first one moment, along with the object then existent, imagine afterwards a change in the time without any VARIATION or INTERRUPTION in the object; in which case it gives us the idea of unity. |