ANIMALS. 211 



L>ut it is happy for mankind, that this state of inquietude is seldom 

 driven to an extreme ; and that there are medicines which seldom fail 

 to give relief. However, man finds it more difficult than any other 

 animal to procure sleep ; and some are obliged to court its approaches 

 for several hours together before they incline to rest. It is in vain 

 that all light is excluded ; that all sounds are removed ; that warmth 

 and softness conspire to invite it : the restless and busy mind still re- 

 tains its former activity; and reason, that wishes to lay down the reins, 

 in spite of herself, is obliged to maintain them. In this disagreeable 

 state, the mind passes from thought to thought, willing to lose the dis- 

 tinctness of perception by increasing the multitude of the images. At 

 last, when the approaches of sleep are near, every object of the ima- 

 gination begins to mix with that next it ; their outlines become in a 

 manner rounder ; a part of their distinctions fade away ; and sleep, 

 that ensues, fashions out a dream from the remainder. 



If then it should be asked from what cause this state of repose pro- 

 ceeds, or in what manner sleep thus binds us for several hours toge- 

 ther, I must fairly confess my ignorance, although it is easy to tell 

 what philosophers say upon the subject. Sleep, says one of them,* 

 consists in a scarcity of spirits, by which the orifices or pores of the 

 nerves in the brain, through which the spirits used to flow into the 

 nerves, being no longer kept open by the frequency of the spirits, 

 shut of themselves ; thus the nerves, wanting a new supply of spirits, 

 become lax, and unfit to convey any impression to the brain. All this, 

 how( ver, is explaining a very great obscurity by somewhat more ob- 

 scure ; leaving, therefore, those spirits to open and shut the entrances 

 to the brain, let us be contented with simply enumerating the effects 

 of sleep upon the human constitution. 



In sleep, the whole nervous frame is relaxed, while the heart and 

 the lungs seem more forcibly exerted. This fuller circulation pro- 

 duces also a swelling of the muscles, as they always find who sleep 

 with ligatures on any part of their body. The increased circulation 

 also, may be considered as a kind of exercise, which is continued 

 through the frame ; and, by this, the perspiration becomes more co- 

 pious, although the appetite for food is entirely taken away. Too 

 much sleep dulls the apprehension, weakens the memory, and unfits 

 the body for labour. On the contrary, sleep too much abridged, ema- 

 ciates the frame, produces melancholy, and consumes the constitution. 

 It requires some care, therefore, to regulate the quantity of sleep, and 

 just to take as much as will completely restore nature, without op- 

 pressing it. The poor, as Otway says, sleep little ; forced, by their 

 situation, to lengthen out their labour to their necessities, they have 

 but a short interval for this pleasing refreshment ; and I have ever 

 been of opinion, that bodily labour demands a less quantity of sleep 

 ihan mental. Labourers and artizans are generally satisfied with about" 

 fteven hours ; but I have known some scholars who usually slept nine-, 

 ind perceived their faculties no way impaired by oversleeping. 



The famous Philip Barretiere, who was considered as a prodigy oj 

 learning at the age of fourteen, was known to sleep regularly twelve 



