118 CIRCULATION OF THE BLOOD. 



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 many different species), and are 

 contained within the viewless interstices of the tissues, are 

 to be regarded as so many different aereal forms, or kinds of 

 vapour. 



And here I would gladly be informed by those who admit 

 corporeal spirits, but of a gaseous or vaporous consistency, in 

 the bodies of animals, whether or not they have the power of 

 passing hither and thither, like distinct bodies independently 

 of the blood? Or whether the spirits follow the blood in its 

 motions, either as integral parts of the fluid or as indissolubly 

 connected with it, so that they can neither quit the tissues nor 

 pass hither nor thither without the influx and reflux, and 

 motion of the blood? For if the spirits exhaling from the 

 blood, like the vapour of water attenuated by heat, exist in a 

 state of constant flow and succession as the pabulum of the tis- 

 sues, it necessarily follows that they are not distinct from this 

 pabulum, but are incessantly disappearing ; whereby it seems 

 that they can neither have influx nor reflux, nor passage, nor yet 

 remain at rest without the influx, the reflux, the passage [or 

 stasis] of the blood, which is the fluid that serves as their vehicle 

 or pabulum. 



And next I desire to know of those who tell us that the spirits 

 are formed in the heart, being compounded of the vapours or 

 exhalations of the blood (excited either by the heat of the heart 

 or the concussion) and the inspired air, whether such spirits are 

 not to be accounted much colder than the blood, seeing that 

 both the elements of their composition, namely, air and vapour, 

 are much colder? For the vapour of boiling water is much 

 more bearable than the water itself; the flame of a candle is 

 less burning than the red-hot snuff, and burning charcoal than 



