REVERY, AND TRANCE. 251 



embraces the mental faculties. When the system is under the influence of 

 disease, the usual course of the phenomena of sleep and dreaming is often 

 disturbed and interrupted ; and when the torpitude extends to the vital organs, 

 the effect produced is death. 



But the chief difficulty in the subject of dreaming remains still to be ac- 

 counted for. How is it possible for thoughts or ideas to exist in the brain, 

 and be continued, while the will, which usually regulates them, and the exter- 

 nal senses which give birth to them, have their continuity of action broken 

 in upon ? I shall endeavour to explain this difficulty in language as familiar 

 as I can employ. 



A certain, but a very small, degree of stimulus applied to any of the cere- 

 bral fibres of the human body, whether sensitive or irritative, instead of sen- 

 sibly exhausting them, seems rather to afford them pleasure ; at least the 

 fibres are able to endure it without becoming torpid, or, which is the same 

 thing, requiring sleep or rest. 



Hence every gentle sight, and every gentle sound, or any other gentle 

 object in nature, to what sense soever it be directed; the still twilight of 

 a summer evening ; the mild lustre of the moon, interwoven with the foliage 

 of forest scenery ; the reposing verdure of a spreading lawn ; soft playful 

 breezes ; the modest fragrance of roses and violets ; the light murmurs of a 

 rippling stream ; the tinkling of a neighbouring sheepfold, and the sound of 

 village bells at a distance, are all stimuli that produce no sensible exhaustion ; 

 and, on this very account, form some of the most agreeable images in nature. 

 In like manner, the orbicular motion of the lips in a sucking infant is a source 

 of so much comfort, and attended with so little exhaustion, that whether 

 sleeping or waking, it will generally be found mimicking the action of suck- 

 ing, when at a distance from its nurse; and, perhaps, not thinking of such 

 action itself. A person who, from habit, has acquired a particular motion of 

 any one of his limbs, a twirl of the fingers, or a swinging of one leg over the 

 other, perseveres in such motion from habit alone, and feels no torpitude or 

 exhaustion in the fibres that are excited, although it might be intolerably 

 fatiguing to another who has never acquired the same custom. 



It is probable, then, that thought, and the action of the vital organs, are of this 

 precise character. We are totally ignorant, indeed, of the mysterious mode 

 by which either the one or the other was produced at first ; but we see enough 

 to convince us that the stimulus is, in both cases, equally pleasing and gentle. 

 And hence both actions continue without exhausting us, except when unduly 

 roused ; and form a habit too pertinacious to be broken through by any ordi- 

 nary opposition. 



Thought, then, is to the sensory that which the motions I have just spoken 

 of are to the, muscles? which are the subjects of them. Both continue alike, 

 whether we be reflecting upon the habit or not: but the habit of thinking is 

 so much older, and consequently so much deeper-rooted, than that of any 

 kind of muscular motion, except the muscular motion of the vital organs, that 

 it is impossible for us to subdue it by the utmost efforts of the will : whence, 

 like the action of the vital organs, it accompanies us, not only at all times 

 when awake, but in all ordinary cases during sleep, and is the immediate and 

 necessary cause of our dreaming. 



Thought can only be exercised upon perceptions introduced into the sen- 

 sory by the organs of external sense; an<3 hence the chief bent of our 

 thoughts must be derived, whether sleeping or waking, from the objects or 

 perceptions that most deeply impress us. The train of thoughts, then, that 

 recurs from habit alone, as in sleep or total retirement from the world, must 

 generally be of this description : in the former case, however, by no means 

 correctly or perfectly ; because there are others also which have a tendency 

 to recur, and neither the will nor the senses are in action to regulate or 

 repress them. Whence, as I have already observed, proceeds a combination 

 of thoughts or ideas, sometimes only in a small degree incongruous, and at 

 other times most wild and heterogeneous ; occasionally, indeed, so fearful 

 and extravagant as to stimulate the senses themselves into a sudden renewal 



