after his friend, Lord Bacon, had published his Norum Organum-his new instrument for opening the door to discovery-Harvey executed the task, and restored “the commerce of the mind and things," putting aside as unfruitful the "commerce of the mind and opinions." Up to his time, in anatomy and physiology, believing was seeing— men saw what Galen said was there. The final appeal was to Galen, not to fact. It is doubtful, considering Harvey's dislike to contention, and his love of a tranquil, unambitious pursuit of science, whether he would have written his book at all, had he not been supported by the new philosophy which had been so recently published, with such pomp and circumstance, by the superb Lord Chancellor of England.

Harvey's treatise on the circulation of the blood occupies eighty octavo pages of moderately-sized print. It is still a model of clear, elaborate, elegant, and scientific exposition, perfectly intelligible, and highly interesting, even to one possessing nothing beyond the most ordinary acquaintance with technical terms. It opens with an introduction, showing how unsatisfactory are all the views which have prevailed from the time of Galen to that of the last writer, Fabricius, upon the subject of the pulse and the action of the heart. The notion they had it is difficult for us even to understand-impossible for us to believe, since the revolution effected by Harvey's tract. It was, that the pulse resulted from the contraction and dilatation of the arteries, which contained a mixture of blood and air; that the air was obtained by suction, and hence that the dilatation of the arteries, like the expansion of a pair of bellows, was the active process, and the collapse the return to the passive condition of these tubes. In short, it was the idea of a general respiration, carried on all through the body; which, however, not being sufficient for "the ventilation and refrigeration of the blood," required to be supplemented by lungs placed about the heart. Such was the vague idea handed down from

Galen, who on this subject is full of contradiction; for while in one place he positively affirms that "the arteries contain only blood," in another portion of his writings he says, "Show us another vessel which draws the absolutely perfect blood from the heart, and distributes it, as the arteries do the spirits, over the body." We need not pause to inquire whether any person had anticipated Harvey in his discovery. Many had groped about the truth, vaguely hinting as they vaguely believed, like the man half-restored to sight who saw men like trees walking. Harvey was the first to see, and cause to be seen, the whole operation. To him is due the whole honour of that. Let us listen to his own words:

"When I first gave my mind to vivesections, as a means of discovering the motions and uses of the heart, and sought to discover these from actual inspection, and not from the writings of others, I found the task so truly arduous, so full of difficulties, that I was almost tempted to think, with Fracastorius, that the motion of the heart was only to be comprehended by God; for I could neither rightly perceive, at first, when the systole and diastole took place, nor when and where contraction occurred, by reason of the rapidity of the motion, which in many animals is accomplished in the twinkling of an eye, coming and going like a flash of lightning, so that the systole presented itself to me now from this point, now from that; the diastole the same; and then everything was reversed, the motions occurring, as it seemed, variously and confusedly together. My mind was therefore greatly unsettled, nor did I know what I should myself conclude, nor what believe from others. At length, by using greater and daily diligence, having frequent recourse to vivesections, employing a variety of animals for the purpose, and collating numerous observations, I thought 1 Galen's Works: "Quod sanguis taught. continetur in arteriis" is the title of the chapter in which the doctrine is

2 Galen's Works, against Erasistratus, De Placitis, &c.

that I had attained to the truth, that I should extricate myself and escape from this labyrinth, and that I had discovered what I so much desired, both the motion and the use of the heart and arteries,-since which time I have not hesitated to expose my views upon these subjects, not only in private to my friends, but also in public in my anatomical lectures, after the manner of the academy of old.

"These views, as usual, pleased some more, others less; some chid and calumniated me, and laid it to me as a crime that I had dared to depart from the precepts and opinions of all anatomists; others desired further explanation of the novelties, which, they said, were both worthy of consideration, and might, perchance, be found of signal use. At length, yielding to the requests of my friends, that all might be made participators in my labours, and partly moved by the envy of others, who, receiving my views with uncandid minds, and understanding them indifferently, have essayed to traduce me publicly, I have been moved to commit these things to the press, in order that all may be enabled to form an opinion both of me and my labours."

In the succeeding chapters he describes with minute fidelity the way in which the heart rises into an erect position, strikes on the chest, and at that moment discharges its blood into the arteries, producing the throb of the pulse. Having done this, he explains what has taken place:"First of all, the auricle contracts, and in the course of its contraction throws the blood (which it contains in ample quantities, as the head of the veins, the storehouse and cistern of the blood,) into the ventricles, which, being filled, the heart moves itself straightway, makes all its fibres tense, contracts the ventricles, and performs a beat, by which beat it immediately sends the blood supplied to it by the auricle into the arteries; the

1 Harvey's Works, p. 19.

right ventricle sending its charge into the lungs, by the vessel which is called vena arteriosa, but which, in structure and function and in all things else, is an artery; the left ventricle sending its charge into the aorta, and through this, by the arteries, into the body at large.'

This, then, is the course of the blood within the heart, from the two cisterns of venous blood-the auricles; it flows into the two ventricles-the right ventricle sends its charge into the lungs, the left into the aorta. What becomes of the blood sent by the right ventricle into the lungs? "The blood percolates the substance of the lungs from the right ventricle of the heart into the pulmonary veins and left ventricle." This is the lesser circulation. What becomes of the blood discharged by the left ventricle into the aorta? The answer to this question is given in the eighth chapter, which, as one of the most interesting historical documents in medical literature, we shall give entire :

"Thus far I have spoken of the passage of the blood from the veins into the arteries "—that is, the percolation through the lungs-" 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 in their adhesion. But what remains to be said upon the quantity and source of the blood which thus passes, is of so novel and unheardof a character, that I not only fear injury to myself from the envy of a few, but I tremble lest I make mankind at large my enemies. So much doth wont and custom, that become as another nature, and doctrine once sown that hath struck deep root, and respect for antiquity, influence all men. Still the die is cast, and my trust is in the love of truth, and the candour that inheres in cultivated minds. And, sooth to say, when I surveyed my mass of evidence,

1 Harvey's Works, p. 31.

whether derived from vivesections and my various reflections on them, or from the ventricles of the heart and the vessels that enter into and issue from them, the symmetry and 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 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; and 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 motion, 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 its 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 then passed through the veins and along the vena cava, and so round to the left ventricle in the manner indicated. Which motion we may be allowed to call circular, in the same way as Aristotle says that the air and the rain emulate the circular motion of the superior bodies; for the moist earth warmed by the sun evaporates; the vapours drawn upwards are condensed, and descending in the form of rain moisten the earth again, and by this arrangement are gene rations of living things produced; and in like manner, too, are tempests and meteors engendered by the cir