"For the blood entering the mesentery by the cœliac artery and the superior and inferior mesenteries proceeds to the intestines, from which along with the chyle that has been attracted into the veins it returns by their numerous ramifications into the vena portæ of the liver, and from this into the vena cava, and this in such wise that the blood in these veins has the same colour and consistency as in other veins, in opposition to what many believe to be the fact. Nor need we hold the improbable belief that two inconveniently opposed movements take place in the whole capillary ramification, namely, movement of the chyle upward, of the blood downward. Is not the thing rather arranged as it is by the consummate providence of nature? For were the chyle mingled with the blood, the crude with the concocted in equal proportions, the result would not be concoction, transmutation, and sanguification, but rather, because they are reciprocally active and passive, a mixture, their union with one another producing something intermediate, precisely as when wine is mixed with water and [in] vinegar and water [oxicratum]. But when a minute quantity of chyle is mingled with a large quantity of blood flowing by, a quantity of chyle that bears no notable proportion to the blood, the effect is the same, as Aristotle says, as when a drop of water is added to a cask of wine, or the contrary; the resulting total is not a mixture, but is either wine or water. So in the dissected mesenteric veins we do not find chyme or chyle and blood, separate or mingled, but only blood, sensibly the same in color and consistency as in the rest of the veins."[14] In a second passage of the same chapter,[15] Harvey returns to this subject; and again, twenty-one years later, in his first exercise to Riolanus, as follows:-- "Our learned author mentions a certain tract of his on the Circulation of the Blood: I wish I could obtain a sight of it; perhaps I might retract. But had the learned writer been so disposed, I do not see but that, having admitted the circular motion of the blood (and in the veins, as he says in the eighth chapter of the third book,[16] the blood incessantly and naturally ascends, or flows back, to the heart, as in all the arteries it descends or departs from the heart), all the difficulties which were formerly felt in connection with the distribution of chyle and the blood by the same channels are brought to an equally satisfactory solution; for all the mooted difficulties vanish when we cease to suppose two contrary motions at once in the same vessels, and admit but one and the same continuous motion in the mesenteric vessels from the intestines to the liver."[17]