It is universally allowed by the writers on optics, that the eye at all times sees an equal number of physical points, and that a man on the top of a mountain has no larger an image presented to his senses, than when he is cooped up in the narrowest court or chamber.  It is only by experience that he infers the greatness of the object from some peculiar qualities of the image; and this inference of the judgment he confounds with sensation, as is common on other occasions.  Now it is evident, that the inference of the judgment is here much more lively than what is usual in our common reasonings, and that a man has a more vivid conception of the vast extent of the ocean from the image he receives by the eye, when he stands on the top of the high promontory, than merely from hearing the roaring of the waters.  He feels a more sensible pleasure from its magnificence; which is a proof of a more lively idea:  And he confounds his judgment with sensation, which is another proof of it.  But as the inference is equally certain and immediate in both cases, this superior vivacity of our conception in one case can proceed from nothing but this, that in drawing an inference from the sight, beside the customary conjunction, there is also a resemblance betwixt the image and the object we infer; which strengthens the relation, and conveys the vivacity of the impression to the related idea with an easier and more natural movement.

No weakness of human nature is more universal and conspicuous than what we commonly call credulity, or a too easy faith in the testimony of others; and this weakness is also very naturally accounted for from the influence of resemblance.  When we receive any matter of fact upon human testimony, our faith arises from the very same origin as our inferences from causes to effects, and from effects to causes; nor is there anything but our experience of the governing principles of human nature, which can give us any assurance of the veracity of men.  But though experience be the true standard of this, as well as of all other judgments, we. seldom regulate ourselves entirely by it; but have a remarkable propensity to believe whatever is reported, even concerning apparitions, enchantments, and prodigies, however contrary to daily experience and observation.  The words or discourses of others have an intimate connexion with certain ideas in their mind; and these ideas have also a connexion with the facts or objects, which they represent.  This latter connexion is generally much over-rated, and commands our assent beyond what experience will justify; which can proceed from nothing beside the resemblance betwixt the ideas and the facts.  Other effects only point out their causes in an oblique manner; but the testimony of men does it directly, and is to be considered as an image as well as an effect.  No wonder, therefore, we are so rash in drawing our inferences from it, and are less guided by experience in our judgments concerning it, than in those upon any other subject.