The difference, so far then, between sleeping and waking seems to be that in the latter we have a greater range of conscious recollections, a larger discourse of reason, and associate ideas in longer trains and more as they are connected one with another in the order of nature; whereas in the former, any two impressions, that meet or are alike, join company, and then are parted again, without notice, like the froth from the wave. So in madness, there is, I should apprehend, the same tyranny of the imagination over the judgment; that is, the mind has slipped its cable, and single images meet, and jostle, and unite suddenly together, without any power to arrange or compare them with others, with which they are connected in the world of reality. There is a continual phantasmagoria: whatever shapes and colours come together are by the heat and violence of the brain referred to external nature, without regard to the order of time, place, or circumstance. From the same want of continuity, we often forget our dreams so speedily: if we cannot catch them as they are passing out at the door, we never set eyes on them again. There is no clue or thread of imagination to trace them by. In a morning sometimes we have had a dream that we try in vain to recollect; it is gone, like the rainbow from the cloud. At other times (so evanescent is their texture) we forget that we have dreamt at all; and at these times the mind seems to have been a mere blank, and sleep presents only an image of death. Hence has arisen the famous dispute, _Whether the soul thinks always?_—on which Mr. Locke and different writers have bestowed so much tedious and unprofitable discussion; some maintaining that the mind was like a watch that goes continually, though more slowly and irregularly at one time than another; while the opposite party contended that it often stopped altogether, bringing the example of sound sleep as an argument, and desiring to know what proof we could have of thoughts passing through the mind, of which it was itself perfectly unconscious, and retained not the slightest recollection. I grant, we often sleep so sound, or have such faint imagery passing through the brain, that if we awake by degrees, we forget it altogether: we recollect our first waking, and perhaps some imperfect suggestions of fancy just before; but beyond this, all is mere oblivion. But I have observed that whenever I have been waked up suddenly, and not left to myself to recover from this state of mental torpor, I have been always dreaming of something, _i.e._ thinking, according to the tenor of the question. Let any one call you at any time, however fast asleep you may be, you make out their voice in the first surprise to be like some one’s you were thinking of in your sleep. Let an accidental noise, the falling of something in the next room, rouse you up, you constantly find something to associate it with, or translate it back into the language of your slumbering thoughts.