After this any one will understand how we may form the idea of an impression and of an idea, and how we way believe the existence of an impression and of an idea.

SECT.  IX.  OF THE EFFECTS OF OTHER RELATIONS AND OTHER HABITS.

However convincing the foregoing arguments may appear, we must not rest contented with them, but must turn the subject on every side, in order to find some new points of view, from which we may illustrate and confirm such extraordinary, and such fundamental principles.  A scrupulous hesitation to receive any new hypothesis is so laudable a disposition in philosophers, and so necessary to the examination of truth, that it deserves to be complyed with, and requires that every argument be produced, which may tend to their satisfaction, and every objection removed, which may stop them in their reasoning.

I have often observed, that, beside cause and effect, the two relations of resemblance and contiguity, are to be considered as associating principles of thought, and as capable of conveying the imagination from one idea to another.  I have also observed, that when of two objects connected to-ether by any of these relations, one is immediately present to the memory or senses, not only the mind is conveyed 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 observed, in order to confirm by analogy, my explication of our judgments concerning cause and effect.  But this very argument may, perhaps, be turned 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 derived from the same principles; that their effects in informing and enlivening our ideas are the same; and that belief is nothing but a more forcible and vivid conception of an idea; it should follow, that that action of the mind may not only be derived 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.

This is the objection; let us now consider its solution.  It is evident, that whatever is present to the memory, striking upon the mind with a vivacity, which resembles an immediate impression, must become of considerable moment in all the operations of the mind, and must easily distinguish itself above the mere fictions of the imagination.  Of these impressions or ideas of the memory we form a kind of system, comprehending whatever we remember to have been present, either to