^66 



ON SLEEP, DREAMING, 



dim wiid-fire, in the pestilent bosom of mists and exhalations, and from 

 their murky shades alluring the incautious inquirer to bogs, and sloughs, 

 and quagmires of wreck and ruin ? 



LECTURE Vn. 



OJI SLEEP, DREAMING, REVERY, AND TRANCE J SLEEP- WALKINO, AND 

 SLEEP-TALKING. 



We are proceeding to a subject of much difficulty in theory, though of 

 the greatest familiarity in fact ; and 1 freely confess to you, that although 

 I have endeavoured to investigate almost every opinion that has been 

 offered upon it, from the time of Aristotle to our own day, I have never 

 met with any thing in the least degree satisfactory, or capable of unravel- 

 ling the perplexities in which it lies entangled. 



What can possibly be more opposite to each other than the two states 

 of wakefulness and sleep ? — the senses in full vigour and activity, alive to 

 every pursuit and braced up to every exertion, — and a suspension of all 

 sense whatever, a looseness and inertness of the voluntary powers, so nearly 

 akin to death, that nothing but a daily experience of the fact itself could 

 justify us in expecting that we could ever recover from it. 

 , And yet, while sucli is the lifelessness without, the mind, now destitute 

 of the control of the will, is often overwhelmed with a chaos of ideas, rush- 

 ing upon each other with so much rapidity, that the transactions of ages 

 are crowded into moments, and so confused and disjointed, that the wildest 

 and most incongruous fancies flit before us, and every thing that is possi- 

 ble becomes united with every thing that is impossible. 



Such, however, are the ordinary means devised by Infinite Wisdom to 

 revivify the animal frame, when exhausted by the labours of the day ; to 

 recruit it for new exertions, and enable it to fill up the measure of its ex- 

 istence. 



The order I shall take leave to pursue in discussing this abstruse sub- 

 ject will consist, first, in a brief examination of the more prominent hy- 

 potheses on sleep and dreaming that have been offered to us by ancient 

 and modern schools : secondly, in a minute analysis of the feelings and| 

 phsenomena by which these operations are characterized, agreeably to the 

 series in which they occur ; thirdly, in submitting the outline of a new 

 theory to explain the entire process ; and lastly, in an application of such 

 theory to a variety of other subjects of a similar and equally extraordinary 

 nature. 



Sleep may be either natural or morbid. The former is usually pro- 

 duced by whatever exhausts the principle of life ; as great muscular ex- 

 citement, violent pain, vehement use of the external senses ; or great 

 mental excitement, as intense thought, or severe distress.^^ M sleep r 

 is commonly occasioned by compression or commotion of* the brain, and , 

 is hence often the result of congestion, plethora, or local injury to the 

 skull. 



Compression and commotion, though less frequent, are more direct 

 and obvious causes : and hence the greater number of physiologists be- 

 lieve compression to take place also, though in a slight degree, in every 



