But in the imagination, besides the pain or pleasure arising from the properties of the natural object, a pleasure is perceived from the resemblance which the imitation has to the original:  the imagination, I conceive, can have no pleasure but what results from one or other of these causes.  And these causes operate pretty uniformly upon all men, because they operate by principles in nature, and which are not derived from any particular habits or advantages.  Mr. Locke very justly and finely observes of wit, that it is chiefly conversant in tracing resemblances; he remarks, at the same time, that the business of judgment is rather in finding differences.  It may perhaps appear, on this supposition, that there is no material distinction between the wit and the judgment, as they both seem to result from different operations of the same faculty of comparing.  But in reality, whether they are or are not dependent on the same power of the mind, they differ so very materially in many respects, that a perfect union of wit and judgment is one of the rarest things in the world.  When two distinct objects are unlike to each other, it is only what we expect; things are in their common way; and therefore they make no impression on the imagination:  but when two distinct objects have a resemblance, we are struck, we attend to them, and we are pleased.  The mind of man has naturally a far greater alacrity and satisfaction in tracing resemblances than in searching for differences; because by making resemblances we produce new images; we unite, we create, we enlarge our stock; but in making distinctions we offer no food at all to the imagination; the task itself is more severe and irksome, and what pleasure we derive from it is something of a negative and indirect nature.  A piece of news is told me in the morning; this, merely as a piece of news, as a fact added to my stock, gives me some pleasure.  In the evening I find there was nothing in it.  What do I gain by this, but the dissatisfaction to find that I had been imposed upon?  Hence it is that men are much more naturally inclined to belief than to incredulity.  And it is upon this principle, that the most ignorant and barbarous nations have frequently excelled in similitudes, comparisons, metaphors, and allegories, who have been weak and backward in distinguishing and sorting their ideas.  And it is for a reason of this kind, that Homer and the oriental writers, though very fond of similitudes, and though they often strike out such as are truly admirable, seldom take care to have them exact; that is, they are taken with the general resemblance, they paint it strongly, and they take no notice of the difference which may be found between the things compared.