I say then, that since we may suppose, but never can conceive a specific deference betwixt an object and impression; any conclusion we form concerning the connexion and repugnance of impressions, will not be known certainly to be applicable to objects; but that on the other hand, whatever conclusions of this kind we form concerning objects, will most certainly be applicable to impressions.
The reason is not difficult.

As an object is supposed to be different from an impression, we cannot be sure, that the circumstance, upon which we found our reasoning, is common to both, supposing we form the reasoning upon the impression.

It is still possible, that the object may differ from it in that particular.

But when we first form our reasoning concerning the object, it is beyond doubt, that the same reasoning must extend to the impression: And that because the quality of the object, upon which the argument is founded, must at least be conceived by the mind; and coued not be conceived, unless it were common to an impression; since we have no idea but what is derived from that origin.
Thus we may establish it as a certain maxim, that we can never, by any principle, but by an irregular kind [Such as that of Sect.

2, form the coherence of our perceptions.] of reasoning from experience, discover a connexion or repugnance betwixt objects, which extends not to impressions; though the inverse proposition may not be equally true, that all the discoverable relations of impressions are common to objects.
To apply this to the present case; there are two different systems of being presented, to which I suppose myself under necessity of assigning some substance, or ground of inhesion.