Circulation of the Blood 143 



unnoticed, it seems that the spirits which flow by 

 the veins or the arteries are not distinct from the 

 blood, any more than the flame of a lamp is distinct 

 from the inflammable vapour that is on fire ; in short, 

 that the blood and these spirits signify one and the 

 same thing, though different, like generous wine and 

 its spirit ; for as wine, when it has lost all its spirit, is 

 no longer wipe, but a vapid liquor or vinegar ; so blood 

 without spirit is not blood, but something else clot or 

 cruor ; even as a hand of stone, or of a dead body, is 

 no hand in the most complete sense, neither is blood 

 void of the vital principle proper blood ; it is imme- 

 diately to be held as corrupt when deprived of its 

 spirit. The spirit therefore which inheres in the 

 arteries, and especially in the blood which fills them, 

 is to be regarded either as its act or agent, in the same 

 way as the spirit of wine in wine, and the spirit of aqua 

 vitae in brandy, or as a flame kindled in alcohol, which 

 lives and feeds on, or is nourished by itself. The 

 blood consequently, though richly imbued with spirits, 

 does not swell, nor ferment, nor rise to a head through 

 them, so as to require and occupy a larger space, a 

 fact that may be ascertained beyond the possibility of 

 question by the two cups of equal size ; it is to be 

 regarded as wine, possessed of a large amount of spirits, 

 or, in the Hippocratic sense, of signal powers of acting 

 and effecting. 



It is therefore the same blood in the arteries that is 

 found in the veins, although it may be admitted to be 

 more spirituous, possessed of higher vital force in the 

 former than in the latter ; but it is not changed into 

 anything more vaporous, or more aereal, as if there 

 were no spirits but such as are aereal, and no cause of 

 action or activity that is not of the nature of flatus or 

 wind. But neither the animal, natural, nor vital spirits 

 which inhere in the solids, such as the ligaments and 

 nerves (especially if they be of so mony different 

 species), and are contained within the viewless inter- 



