116 CIRCULATION OF THE BLOOD. 



whose nature is thus left so wholly ambiguous, should serve as 

 the common subterfuge of ignorance. Persons of limited infor- 

 mation, when they are at a loss to assign a cause for anything, 

 very commonly reply that it is done by the spirits ; and so they 

 bring the spirits into play upon all occasions ; even as indif- 

 ferent poets are always thrusting the gods upon the stage as 

 a means of unravelling the plot, and bringing about the 

 catastrophe. 



Fernelius, and many others, suppose that there are aereal 

 spirits and invisible substances. Fernelius proves that there are 

 animal spirits, by saying that the cells in the brain are ap- 

 parently unoccupied, and as nature abhors a vacuum, he con- 

 cludes that in the living body they are filled with spirits, just as 

 Erasistratus had held that, because the arteries were empty of 

 blood, therefore they must be filled with spirits. But Medical 

 Schools admit three kinds of spirits : the natural spirits flowing 

 through the veins, the vital spirits through the arteries, and the 

 animal spirits through the nerves ; whence physicians say, out 

 of Galen, that sometimes the parts of the brain are oppressed 

 by sympathy, because the faculty with the essence, i. e., the 

 spirit, is overwhelmed; and sometimes this happens inde- 

 pendently of the essence. Farther, besides the three orders of 

 influxive spirits adverted to, a like number of implanted or 

 stationary spirits seem to be acknowledged ; but we have found 

 none of all these spirits by dissection, neither in the veins, nerves, 

 arteries, nor other parts of living animals. Some speak of cor- 

 poreal, others of incorporeal spirits ; and they who advocate 

 the corporeal spirits will have the blood, or the thinner por- 

 tion of the blood, to be the bond of union with the soul, the 

 spirit being contained in the blood as the flame is in the smoke 

 of a lamp or candle, and held admixed by the incessant motion 

 of the fluid ; others, again, distinguish between the spirits and 

 the blood. They who advocate incorporeal spirits have no 

 ground of experience to stand upon; their spirits indeed are 

 synonymous with powers or faculties, such as a concoctive 

 spirit, a chylopoietic spirit, a procreative spirit, &c. they admit 

 as many spirits, in short, as there are faculties or organs. 



But then the schoolmen speak of a spirit of fortitude, pru- 

 dence, patience, and the other virtues, and also of a most holy 

 spirit of wisdom, and of every divine gift ; and they besides 



