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ceafe to follicit our Senfes, and the Will does no 
longer determine the Spirits into the Mufcles of vo- 
luntary Motion 5 which two Kind of Actions, as well 
as the Operations and Paffions of our Mind,, do, in 
the Day-time, make ftrong Derivations of the Spirits 
from the natural and vital Funftions j which, for that 
reafon, are never fo perfed as in found and undifturfa- 
ed Sleep. 
Thofe who are acquainted with the Doftrine of 
Derivations and Revulfions, founded upon innume- 
rable Obfervations in the Animal Oeconomy and 
Practice of Phyfick, do know, that a Flux of any 
of the animal Fluids arifing from Nature, or from a 
Difeafe, or provoked by Art to any one or more Parts 
of the Body, or to any Organ of Secretion or Excre- 
tion, will caufe a fenfible proportional Diminution of 
the Afflux to, and of the Secretion and Execretion 
by the other Parts and Organs. 
Therefore fo foon as a Deficiency of animal Spi- 
rits happens by Labour, or from any other Caufe 
whatever, that Defed will be firft felt in the Organs 
of Senfation, the Mufcles of voluntary Motion, and 
the Operations of our Mind ; becaufe thefe are not 
acted upon by fuch powerful and irrefiftible Agents, 
as the Organs of the natural and vital Fundionsare 
in perfed Health 5 for the Mind being fenfible of 
the Defed of Spirits for its Aftions and Operations, 
choofeth to forbear 5 we retire from external Objects, 
and then the Whole of the remaining Spirits are led to 
the natural and vital Organs, by the Mechanifm 
above defcribed 5 and the Organs of Senfation and 
voluntary Motion muft be entirely deferted by them 
for that time j which is the State of Sleep, and 
which 
