1 66 Circulation of the Blood 



the lungs, which is, because it is thinner, as having 

 there to undergo filtration. 



Still further; from the summary which precedes, and 

 by way of satisfying those who are importunate in 

 regard to the causes of the circulation, and incline to 

 regard the power of the heart as competent to every- 

 thing as that it is not only the seat and source of the 

 pulse which propels the blood, but also, as Aristotle 

 thinks, of the power which attracts and produces it ; 

 moreover, that the spirits are engendered by the heart, 

 and the influxive vital heat, in virtue of the innate heat 

 of the heart, as the immediate instrument of the soul, 

 or common bond and prime organ in the performance 

 of every act of vitality ; in a word, that the motion, 

 perfection, heat, and every property besides of the 

 blood and spirits are derived from the heart, as their 

 fountain or original, (a doctrine as old as Aristotle, who 

 maintained all these qualities to inhere in the blood, as 

 heat inheres in boiling water or pottage,) and that the 

 heart is the primary cause of pulsation and life ; to those 

 persons, did I speak openly, I should say that I do not 

 agree with the common opinion ; there are numerous 

 particulars to be noted in the production of the parts 

 of the body which incline me this way, but which it 

 does not seem expedient to enter upon here. Before 

 long, perhaps, I shall have occasion to lay before the 

 world things that are more wonderful than these, and 

 that are calculated to throw still greater light upon 

 natural philosophy. 



Meantime I shall only say, and, without pretending 

 to demonstrate it, propound with the good leave of 

 our learned men, and with all respect for antiquity 

 that the heart, with the veins and arteries and the 

 blood they contain, is to be regarded as the beginning 

 and author, and fountain and original of all things in the 

 body, the primary cause of life ; and this in the same 

 acceptation as the brain with its nerves, organs of sense 

 and spinal marrow inclusive, is spoken of as the one 



