T 1.3.9.2

I have often observ'd, that, beside cause and effect, the two relations of resemblance and contiguity, are to be consider'd as associating principles of thought, and as capable of conveying the imagination from one idea to another. I have also observ'd, that when of two objects connected together by any of these relations, one is immediately present to the memory or senses, not only the mind is convey'd to its co-relative by means of the associating principle; but likewise conceives it with an additional force and vigour, by the united operation of that principle, and of the present impression. All this I have observ'd, in order to confirm by analogy, my explication of our judgments concerning cause and effect. But this very argument may, perhaps, be turn'd against me, and instead of a confirmation of my hypothesis, may become an objection to it. For it may be said, that if all the parts of that hypothesis be true, viz. that these three species of relation are deriv'd from the same principles; that their effects in inforcing and inlivening our ideas are the same; and that belief is nothing but a more forcible and vivid conception of an idea; it shou'd follow, that that action of the mind may not only be deriv'd from the relation of cause and effect, but also from those of contiguity and resemblance. But as we find by experience, that belief arises only from causation, and that we can draw no inference from one object to another, except they be connected by this relation, we may conclude, that there is some error in that reasoning, which leads us into such difficulties.