In lieu of an abstract, here is a brief excerpt of the content:

112 BOOK THREE Question 1: Whether veins are necessary in an animal body. E HAVE ALREADY discussed the disposition of the members ,”1 etc. With respect to this third book we will first ask whether veins are necessary in an animal body. 1. It seems not. The natural power [vis naturalis] is in charge of providing nourishment for plants and in animals.2 But there are no veins in plants delegated for nourishment. But a vein does not exist for another purpose, and therefore veins are not necessary. 2. Moreover, bones are nourished just like other members, but there are no veins in bones.3 It is therefore not necessary to posit the existence of veins in other parts for the sake of the distribution [delegatio] of nourishment. 3. Moreover, the conversion of the nutriment is almost completed in the third digestion, but veins are not required during the third digestion, and are therefore not required in the other digestions either. To the contrary: every bodily operation occurs by means of an intermediate body. But the distribution of the nutriment is a bodily operation, as is clearly evident in its own right [de se]. Therefore, it occurs by means of a bodily medium. But such a medium is nothing other than a vein; therefore, etc. One must reply that the word “vein” is an equivocal noun which has two meanings.4 These are “pulsating,” which is properly called an artery, and “non-pulsating,” which is proper- “ 1. Ar., HA 3.1 (509a27–30); cf. A., DA 3.1.1.1 (SZ 1: 344). 2. A., DA 20.2.3.73 (SZ 2: 1399). 3. A., DA 16.2.6.124 (SZ 2: 1223). 4. Simplifying the unnecessarily duplicative vena nomen aequivocum est ad duo vel duplex est . . . BOOK THREE 113 ly called a vein in the human.5 Now, a pulsating vein (that is, an artery) is necessary for the sake of sustaining the heat or to bear the spirit to individual members. Since these members are like a medium for life, their arteries arise on the left side of the heart, where the heart’s heat and the spirit are especially abundant . But a non-pulsating vein is necessary for the distribution of the nutriment, that is, the humors, to individual members and for the sake of sustaining the heat and the spirits and to restore what has been lost, because when aliment [alimentum] is received into a particular part, it will be unable to restore whatever has been lost in these individual members unless it has access to individual members. Moreover, everything that has a part in which it is generated, has also a part in which it is kept; otherwise, it would be generated in vain. But the blood is generated in a given part in the body such as in the liver and the heart.6 It therefore requires a part in which it is kept. But this part is the vein, and this is why, etc. Nevertheless, one must observe that sometimes the blood is in a remote power, and sometimes it is in a power that is close to conversion, and sometimes it is in a middle power.7 When it is in the stomach it is in a remote power. From there it has a pathway through which it comes to the stomach (like the esophagus) and a pathway through which it is distributed from the stomach (like the delicate or mesenteric pathways through which it is sent to the liver). It is in a power close [to conversion] when it is dispatched to a given member, and then it requires no connection beyond the member. But it exists in a middle power in the liver where the second digestion occurs, and this is why the liver requires veins through which the blood may be dispatched to other members and through which it can receive the moistures not converted into blood as a sediment [hypostasis].8 And this is why the veins are necessary. 5. A., DA 1.2.20.381 (SZ 1: 189). 6. Cf. A., DA 1.3.5.601 (SZ 1: 275). 7. A., DA 3.1.1.1. On a remote or proximate power, see also QDA 9.18 (211, 1–5). The former can result in diverse effects; the latter seems determined to a single effect. 8. A., DA 3.1.3.100 (SZ 1: 393–94). Hypostasis usually means “sediment” or “dregs,” as at QDA 15.16...

Share