The next chapter is devoted to the description of the manner in which the blood passes through the substance of the lungs from the right ventricle of the heart into the pulmonary veins. It is followed by the glorious eighth chapter, in which Harvey's style, always impressive and solid, rises into real eloquence, for a great occasion justifies the use of repetitions, of antitheses and an abundance of metaphors. He now quits the method of demonstration and experiment for that of indirect but irrefragable argument. He deals with the quantity of blood passing through the heart from the veins to the arteries, and again brings together all his threads to a nodal point. "Thus far I have spoken of the passage of the blood from the veins into the arteries, and of the manner in which it is transmitted and distributed by the action of the heart; points to which some, moved either by the authority of Galen or Columbus, or the reasonings of others, will give their adhesion. But what remains to be said upon the quantity and source of the blood which thus passes is of a character so novel and unheard of that I not only fear injury to myself from the envy of a few, but I tremble lest I have mankind at large for my enemies, so much doth wont and custom become a second nature. Doctrine once sown strikes deeply its root, and respect for antiquity influences all men. Still the die is cast, and my trust is in my love of truth and the candour of cultivated minds. And sooth to say when I surveyed my mass of evidence, whether derived from vivisections and my various reflections on them, or from the study of the ventricles of the heart and the vessels that enter into and issue from them, the symmetry and the size of these conduits, for Nature doing nothing in vain, would never have given them so large a relative size without a purpose--or from observing the arrangement and intimate structure of the valves in particular and of the other parts of the heart in general, with many things besides, I frequently and seriously bethought me and long revolved in my mind, what might be the quantity of blood which was transmitted, in how short a time its passage might be effected and the like. But not finding it possible that this could be supplied by the juices of the ingested aliment without the veins on the one hand becoming drained, and the arteries on the other getting ruptured through the excessive charge of blood, unless the blood should somehow find its way from the arteries into the veins and so return to the right side of the heart; I began to think whether there might not be a movement, as it were, in a circle. Now this I afterwards found to be true, and I finally saw that the blood, forced by the action of the left ventricle into the arteries, was distributed to the body at large and in several parts in the same manner as it is sent through the lungs impelled by the right ventricle into the pulmonary artery, and that it