For if we can find any such objects, we may certainly conclude, from the foregoing principle, that they are very naturally confounded with identical ones, and are taken for them in most of our reasonings.

But though this question be very important, it is not very difficult nor doubtful.

For I immediately reply, that a succession of related objects places the mind in this disposition, and is considered with the same smooth and uninterrupted progress of the imagination, as attends the view of the same invariable object.

The very nature and essence of relation is to connect our ideas with each other, and upon the appearance of one, to facilitate the transition to its correlative.

The passage betwixt related ideas is, therefore, so smooth and easy, that it produces little alteration on the mind, and seems like the continuation of the same action; and as the continuation of the same action is an effect of the continued view of the same object, it is for this reason we attribute sameness to every succession of related objects.