our internal perception or senses; and every particular of that system, joined to the present impressions, we are pleased to call a reality.  But the mind stops not here.  For finding, that with this system of perceptions, there is another connected by custom, or if you will, by the relation of cause or effect, it proceeds to the consideration of their ideas; and as it feels that it is in a manner necessarily determined to view these particular ideas, and that the custom or relation, by which it is determined, admits not of the least change, it forms them into a new system, which it likewise dignifies with the title of realities.  The first of these systems is the object of the memory and senses; the second of the judgment.

It is this latter principle, which peoples the world, and brings us acquainted with such existences, as by their removal in time and place, lie beyond the reach of the senses and memory.  By means of it I paint the universe in my imagination, and fix my attention on any part of it I please.  I form an idea of Rome, which I neither see nor remember; but which is connected with such impressions as I remember to have received from the conversation and books of travellers and historians.  This idea of Rome I place in a certain situation on the idea of an object, which I call the globe.  I join to it the conception of a particular government, and religion, and manners.  I look backward and consider its first foundation; its several revolutions, successes, and misfortunes.  All this, and everything else, which I believe, are nothing but ideas; though by their force and settled order, arising from custom and the relation of cause and effect, they distinguish themselves from the other ideas, which are merely the offspring of the imagination.

As to the influence of contiguity and resemblance, we may observe, that if the contiguous and resembling object be comprehended in this system of realities, there is no doubt but these two relations will assist that of cause and effect, and infix the related idea with more force in the imagination.  This I shall enlarge upon presently.  Mean while I shall carry my observation a step farther, and assert, that even where the related object is but feigned, the relation will serve to enliven the idea, and encrease its influence.  A poet, no doubt, will be the better able to form a strong description of the Elysian fields, that he prompts his imagination by the view of a beautiful meadow or garden; as at another time he may by his fancy place himself in the midst of these fabulous regions, that by the feigned contiguity he may enliven his imagination.