12 ON THE HEART AND BLOOD. 



tain the same blood as the veins, and nothing but the same 

 blood. Some, whilst they attempt to lessen the difficulty here, 

 affirming that the blood is spirituous and arterious, virtually 

 concede that the office of the arteries is to carry blood from the 

 heart into the whole of the body, and that they are therefore 

 filled with blood ; for spirituous blood is not the less blood on 

 that account. And then no one denies that the blood as such, 

 even the portion of it which flows in the veins, is imbued with 

 spirits. But if that portion which is contained in the arteries 

 be richer in spirits, it is still to be believed that these spirits are 

 inseparable from the blood, like those in the veins; that the blood 

 and spirits constitute one body (like whey and butter in milk, or 

 heat [and water] in hot water), with which the arteries are charged, 

 and for the distribution of which from the heart they are pro- 

 vided, and that this body is nothing else than blood. But if this 

 blood be said to be drawn from the heart into the arteries by 

 the diastole of these vessels, it is then assumed that the arteries 

 by their distension are filled with blood, and not with the am- 

 bient air, as heretofore ; for if they be said also to become 

 filled with air from the ambient atmosphere, how and when, I 

 ask, can they receive blood from the heart ? If it be answered : 

 during the systole ; I say, that seems impossible ; the arteries 

 would then have to fill whilst they contracted ; in other words, 

 to fill, and yet not become distended. But if it be said : during 

 the diastole, they would then, and for two opposite purposes, be 

 receiving both blood and air, and heat and cold ; which is im- 

 probable. Further, when it is affirmed that the diastole of the 

 heart and arteries is simultaneous, and the systole of the two is 

 also concurrent, there is another incongruity. For how can 

 two bodies mutually connected, which are simultaneously dis- 

 tended, attract or draw anything from one another; or, being 

 simultaneously contracted, receive anything from each other? 

 And then, it seems impossible that one body can thus at- 

 tract another body into itself, so as to become distended, 

 seeing that to be distended is to be passive, unless, in the 

 manner of a sponge, previously compressed by an external 

 force, whilst it is returning to its natural state. But it is 

 difficult to conceive that there can be anything of this kind in 

 the arteries. The arteries dilate, because they are filled like 

 bladders or leathern bottles ; they are not filled because they 



