Taut' oun eis heautas helkousin hai artêriai pantachothen, hai men eis to derma kathêkousai ton exôthen aera; plêsion te gar autais houtos esti kai kouphotatos en tois malista; tôn d' allôn hê men epi ton trachêlon ek tês kardias aniousa kai hê kata rhachin, êdê de kai hosai toutôn engys ex autês malista tês kardias; hosai de kai tês kardias porrhôterô kai tou dermatos, helkein tautais anankaion ek tôn phlebôn to kouphotaton tou haimatos; hôste kai tôn eis tên gastera te kai ta entera kathêkousôn artêriôn tên holkên en tô diastellesthai gignesthai para te tês || kardias autês 206 kai tôn parakeimenôn autê phlebôn pampollôn ousôn. ou gar dê ek ge tôn enterôn kai tês koilias trophên houtô pacheian te kai bareian en heautois echontôn dynantai ti metalambanein, ho ti kai axion logou, phthanousai plêrousthai tois kouphoterois. oude gar ei katheis auliskon eis angeion hydatos te kai psammou plêres epispasaio tô stomati ton ek tou auliskou aera, dynait' an akolouthêsai soi pro tou hydatos hê psammos; aei gar en tê pros to kenoumenon akolouthia to kouphoteron hepetai proteron. XV It is not to be wondered at, therefore, that only a very little [nutrient matter] such, namely, as has been accurately elaborated--gets from the stomach into the arteries, since these first become filled with lighter matter. We must understand that _there are two kinds of attraction_, that by which a vacuum becomes refilled and that caused by appropriateness of quality;[392] air is drawn into bellows in one way, and iron by the lodestone in another. And we must also understand that the traction which results from evacuation acts primarily on what is light, whilst that from appropriateness of quality acts frequently, it may be, on what is heavier (if this should be naturally more nearly related[393]). Therefore, in the case of the heart and the arteries, it is in so far as they are hollow organs, capable of diastole, that they always attract the lighter matter first, while, in so far as they require nourishment, it is actually into their _coats_ (which are the real _bodies_ of these organs) that the appropriate matter is drawn.[394] Of the blood, then, which is taken into their cavities when they dilate, that part which is most proper to them and most able to afford nourishment is attracted by their actual coats.