greek underpinnings to his methodology in unraveling de motu cordis and what harvey has to teach us...

International Journal of Cardiology xxx (2013) xxx–xxx

IJCA-16830; No of Pages 10

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International Journal of Cardiology

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Greek underpinnings to his methodology in unraveling De Motu Cordis and whatHarvey has to teach us still today☆

Ares Pasipoularides ⁎Department of Surgery, Duke University School of Medicine, Durham, NC 27710, USA

☆ The author takes responsibility for all aspects of the reof the data presented and their discussed interpretation. Tinterest.⁎ 12 Cogswood Rd., Asheville, NC 28804. Tel.: +1 828 2

E-mail address: [email protected].

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Article history:Received 23 July 2013Accepted 25 July 2013Available online xxxx

Keywords:Harvey’s extension of Aristotle andtransformation of GalenGreek natural philosophy and Harveianstructure–function correlationsHarvey’s Socratis regula or Socrates’ rule forinterrogation across numerous animal speciesSystolic contraction as themotus proprius orcharacteristic action of the heartHarvey’s study of arterial pulsatile flowHistorical continuity in the methodology ofmodern medical science

William Harvey’s writings betray amazing insights born out of countless hours of thoughtful experimentation.Throughout his life, Harvey worked as a tireless and thoughtful researcher and a transmitter and intermediarybetween the ancient Greek natural philosophers and physicians and the “moderns,” for whom he founded twoforward-looking, interlinked sciences: modern physiology and nascent cardiology. Harvey's methodology anddemonstrations were of such fundamental and standardizing nature as to secure the sure progress of thesetwo sciences. Thus, he rendered to them such a service as Descartes’s cogito ergo sum furnished to Philosophyin giving it a rational standard of certainty, for want of which the more speculative minds of that era were inun-dated with extraordinary conjectures. If Harvey disproved Galen, he absorbed and continued in his physiologicresearch many a principle from Aristotle, whose supreme disciple he remains. The guidance and authority ofAristotle were strong with him to the end. Harvey's account of the motions of the heart and blood in the circula-tion demonstrated that complex physiological systems can be represented in straightforward mechanical terms,a conceptwhichhas remained fundamental to the present day. The philosophical implication ofWilliamHarvey’sdiscovery of the circulation of the bloodwas the resolute application of the experimentalmethod to cardiology. Inmy judgment, he established today’s forward-looking discipline of translational cardiovascular research. In duecourse, he should be widely acknowledged to have done so.

© 2013 Elsevier Ireland Ltd. All rights reserved.

Whatsoever things (are) objects of sight, hearing, (and) experience—these things I hold in higher esteem.—Heraclitus [frag. 55] [1]

Prior to Harvey, the history of medical opinion on the subject of the cir-culation provides quite a remarkable example of the errors into whicheven exceptional minds may wander, by neglecting or misconstruingobservation. During the centuries preceding him, there existed manyanatomists of considerable distinction. Human corpses were availableto them, and they performed experiments on living animals too. More-over, their investigations seem to have been well conducted and theirdiscoveries were undeniably important; nonetheless, as far as the truefunctions of the heart and the blood vessels are concerned, hardly aflicker of real knowledge seems to have dawned upon them. It is truethat many observations that they must have made were indisputablyat variance with the prevailing doctrines. The arteries had been seento discharge blood when wounded; they had been known to emptythemselves when between a ligature and the extremities, whereaswhen ligated, the corresponding part of a vein became swollen and

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reek underpinnings to his meoi.org/10.1016/j.ijcard.2013.

distended. Nevertheless, such pertinent observations had failed toevoke a correct view of the subject, a fact that todaymanyfind puzzling.

However, investigators and scientists from different eras should bejudged in the context of their own times. The ancient Greeks, includingGalen (131–201 CE) and his predecessors, strived to generate soundconceptual systems based on data available to them, and WilliamHarvey built exceptionally effectively on the rich foundation of theirlearning, scholarship, andwisdom [2,3]. As he pointed out in his SecondDisquisition to JohnRiolan the son, his ardent Parisian antagonistwhomhe described as the most experienced physician in the Universitie ofPari: “But no kind of science can possibly flow, save from some pre-existing knowledge of more obvious things” [4].

2. Galen’s views regarding the movements of the blood, in nuce

To properly appreciate Harvey’s epoch-making discovery, it is in-structive to review, in nuce, the theory of the Greek physician Galen –

prevalent in Europe at the time – regarding the movements of theblood [2,3,5]. It was predicated on the following tenets: (1) the liveras the source of the veins and blood; (2) the communication from theright to the left side of the heart through minute and invisible “porosi-ties” in the interventricular septum; (3) the absence of any circularmovement of the blood propelled by the heart—blood was not per-ceived to circulate but rather to slowly ebb and flow; and (4) thepresence of three essential pneumata or spirits.

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2 A. Pasipoularides / International Journal of Cardiology xxx (2013) xxx–xxx

Looked at a bit closer, the Galenic paradigm was based on the threePlatonic spirits and systems, which were controlled by the liver, theheart, and the brain and on the hypothesis that all organs and systemsfunctioned bymeans of faculties, such as attraction, retention, and expul-sion. These faculties rationalized the operation of bodily organs, aswell asthemovement of nutriments and pneuma, or spirit (a sort of enabling en-ergy), into and through the body; failure of their function was a cause ofdisease. The liver, for example, attracted nutriment from vesselsconnecting it to the stomach and intestine and “concocted” or processedit into blood endowedwith physikon pneuma, or natural spirit,whichwasthen attracted into the veins. The veins, in turn, permitted this blood toflow to all the parts of the body, which attracted it to maintain andgrow or heal different tissues or passed it through as invisible transpira-tion or as perspiration. Somebloodwas also attracted by the heart, whichthen discharged it via the vena arteriosa (pulmonary artery) into thelungs, to nourish them. Some of the blood also passed directly from theright to the left ventricle, through small “porosities” in the trabeculatedinterventricular septum. Blood emerging through these porosities wasthen combined in the left ventricle with zotikon pneuma entering byway of the lungs, pulmonary veins, and left auricle; this vital spirit withblood mixture was “concocted” by the heat generated by the heart, andthe waste vapors were expelled back to the lung by regurgitatingthrough the mitral valve. The latter process was made possible by thecomparative insufficiency (remarkably, a postulated functional attribute)of the mitral valve opening into the left ventricle [3]. Once refined in theleft ventricle, the pneuma-vitalized blood was ejected into the aorta andthe systemic arteries. Galen thought that arteries had an expansive “fac-ulty” that originated in the heart and pulsed outward along the arterialwalls, drawing the blood along, much as a bellows is expanded to suckin air and is then contracted to force it out again (cf. Fig. 3). Galen sup-posed that pneuma reached the brain both mixed with arterial bloodand directly, via the nostrils. In the brain, it was processed into psychikonpneuma, psychic spirit or the soul, giving rise to thought and psychic phe-nomena, and was drawn into the nerves to give rise to the senses and tosensitize and move the voluntary muscles and other bodily parts.

3. Aristotle and Harvey’s methodological strategies

That Aristotle’s (384–322 BCE) works had a profound impact onHarvey’s methods is well known, as is much of the corroborative evi-dence for this opinion [6–9]. Aristotelianism encompasses the idea ofthe heart as the key organ and its centrality in research, the view thatmechanistic materialism was inadequate and the enquiry for the teleo-logical explanation (real purpose) of the circulation, the comparisons ofanatomy and function of bodily organs and systems across a wide rangeof species, the approach to embryology through epigenesis rather thanpreformationism, and so on. Against mechanistic materialism and a na-ture without design or purpose, Aristotle constructed a natural philoso-phy that made nature a purposeful agent, and Harvey espoused this.

There is a remarkable order of magnitude analysis in book I, chapterXIII, of Aristotle’sMeteorologica [10] bywhich he argues against the pos-tulate that the rivers are supplied with water by definite undergroundreservoirs, which fill up in the winter and then are gradually depletedduring the summer. Aristotle posits that it should be clear to anyonemaking the rough calculation of the amount of water flowing in a dayand then envisaging the size of the requisite reservoir, that it wouldhave to be as enormous as the size of the earth (or, at least, not fall farshort of it) to receive the total water flowing in a year.

Harvey appears to have been inspired by Aristotle to make acompletely analogous order of magnitude analysis [3] in De Motu Cordis,chapter IX: By estimating the volume of blood in the left ventricle andthe rate atwhich itflowed into the aorta, he concluded that prevailingGa-lenic views regarding the movements of the blood were incorrect. Con-temporary thought posited that blood was created in the liver beforepassing through the heart and being consumed by the body. Harvey'smeasurements suggested that the rate atwhich bloodwas being pumped

Please cite this article as: Pasipoularides A, Greek underpinnings to his meus still today, Int J Cardiol (2013), http://dx.doi.org/10.1016/j.ijcard.2013.

out of the heart would necessitate an impossibly large volume of blood tobegin with for traditional models to be correct [3].

Observations of the heart's one-way valve system and an apprecia-tion of cycles in nature instilled through his Aristotelian educationhelped Harvey to conceive circulation. By both Aristotle’s and Harvey’sarguments, the amount of liquid flowing (viz., river water/blood) is toocopious for the opposed postulate (viz., definitewater reservoirs/Galeniccontinual blood formation from digested food for complete consump-tion by the body) to be accepted by a reasonable observer [3]. AsAristotle’s major discussion of the water cycle is in the same chapter oftheMeteorologica as his order of magnitude analysis of water reservoirs,it is to be expected that Harvey was aware of Aristotle’s quantitative ar-gument on rivers and reservoirs.

4. Convenient practical aids from Comparative Physiology

Following Aristotle’s example and comparing anatomy and functionof bodily organs and systems across numerous species, Harvey benefit-ed immeasurably. In chapter IV of De Motu Cordis, he relates [11], “Wehave a small shrimp in these countries, which is taken in the Thamesand in the sea, the whole of whose body is transparent; this creature,placed in a little water, has frequently afforded myself and particularfriends an opportunity of observing the motions of the heart with thegreatest distinctness, the external parts of the bodypresentingno obsta-cle to our view, but the heart being perceived as though it had been seenthrough a window.” Fascinating!

Moreover, through his comparative anatomy and physiology inves-tigations, he discovered that he could, in effect, slow down the rate ofevolution of physiological processes. Indeed, in chapter I of De MotuCordis, he recounts [11], “When I first gave my mind to vivisections, asa means of discovering the motions and uses of the heart, and soughtto discover these from actual inspection, and not from the writings ofothers, I found the task so truly arduous, so full of difficulties, that Iwas almost tempted to think, with Fracastorius, that the motion of theheart was only to be comprehended by God. For I could neither rightlyperceive at first when the systole and when the diastole took place,nor when and where dilatation and contraction occurred, by reason ofthe rapidity of the motion, which in many animals is accomplished inthe twinkling of an eye, coming and going like a flash of lightning; sothat the systole presented itself to me now from this point, now fromthat; the diastole the same; and then everything was reversed, the mo-tions occurring, as it seemed, variously and confusedly together. Mymindwas therefore greatly unsettled nor did I knowwhat I should my-self conclude, nor what believe from others. I was not surprised thatAndreas Laurentius should have written that the motion of the heartwas as perplexing as the flux and reflux of Euripus (see below) hadappeared to Aristotle.”

To get out of the quandary, he eventually developed the strategy toundertake experiments on cold-blooded animals, such as toads, snakes,frogs, snails, lobsters, shellfish, mollusks, shrimp, and small fish, and ondying warm-blooded animals, such as dogs and pigs, where the heartbeats more slowly. Thus, he was enabled to see and ascertain what themotions of the heart chambers really are and how they evolve in time.One of Harvey’s contemporaries in Padua, Galileo (1564–1642), sharedsuch an aspiration to slow down nature in order to discern clearly andstudy phenomena that interested him more precisely. Galileo hadresorted to his inclined plane experiments, allowing accelerationunder gravity to be examined in more detail than was feasible with ob-jects in free fall [12]. Greatminds naturally think along parallel lines.Wecan also speculate whether they had discussed the issue betweenthemselves.

5. Harvey's Socratis regula per similitudinem

Harvey invoked and subscribed to what he called “the rule ofSocrates,” his Socratis regula, to elicit the truth by observing and



3A. Pasipoularides / International Journal of Cardiology xxx (2013) xxx–xxx

interrogating both the isolated and the in situ interactive performance ofthe heart and the other components of the circulatory system across alarge diversity of species while contemplating a coherent causal under-standing. He applied this term in his Prelectiones [13,14], in the sectionon Canones anatomiae generalis, which are a set of rules or suggestionsand heuristics for theproper performance of anatomy; however, this So-cratic Method is central to all of Harvey’s published works. Harvey rea-soned that going about looking for the same thing in different contextsby observing across animal species – complying with his rule ofSocrates – we can assess and contrast, and thus discern, similaritiesand differences in organs and functions that would otherwise be obscure,if we limited investigation to a single species. On p. 20 of his Prelectiones,he wrote (in his distinctive mélange of Latin and English) “Hinc Socratisregula per similitudinem in a great print” [13]. It appears that he had inmind the passage in Plato’s Republic where Socrates (469–399 BCE) issuggesting a method of inquiry which will render the obscure clear,just as a nearby inscription in big lettering stands out sharper than adistant one in small [15]. Harvey may have come upon his rule ofSocrates through Galen, who had adapted Socratic methods to medicalscientific practice; he was acquainted with Galen's De Hippocratis etPlatonis Placitis, in which Galen takes his reader through the compare-and-contrast methodology of the per similitudinemmethod [16].

Following Galen, Socrates, and Plato (429–347 BCE), Harvey'sSocratis regula per similitudinem is his approach to comparative anato-my, and he considers it essential in order to figure out the usefulness,function, purpose, and necessity of bodily organs. In Aristotelian terms,it defines the what-it-is-to-be a heart, in the context of the De MotuCordis. Harvey found that, despite the fact that morphologically, thehearts of numerous animal species differed substantially, focusing onthe pivotal question of function, every single one worked to eject bloodin forceful systole and in so doing generated the arterial pulse, also inthepulmonary artery, aswell as the precordial apical thrust. The forcefulsystole is, consequently, the heart's motus proprius, i.e., its unique, char-acteristic action whereby it fulfills its function (viz. maintenance of thecirculation) in the body.

Thus, on pp. 65–66, in chapter XVII of De Motu Cordis, he takes hisSocratis regula as the principle that explains how the very different con-ditions in the fetus and the adult heart demand very different cardiacstructural characteristics, although the samemotus proprius powerfullyexpels the blood in systole. He notes that in the fetus, while both ventri-cles have the shared purpose of the expulsion of blood into the aorta,they are similar in appearance: “As in the double kernels of a (wal)nut, they about equal each other, and the tip of the right reaches theapex of the left, so that the heart appears as a double-pointed cone”[17]. In contrast, after birth, with the blood now passing from the rightventricle through the lungs, the right ventricle has a smaller burdenthan the left; for that reason, it acquires a thinner structure: “The rightventricle is a sort of servant to the left, it does not reach to the apex,its walls are threefold thinner, and it is somehow joined on to the left,as Aristotle says” [17]. Similar to the myocardial walls, Harvey notedthat the cardiac valves too differ in the precision, redundancy and tight-ness with which their leaflets can close according to the functional de-mands placed on them.

This insightful, comprehensive methodological approach was em-phasized strongly by Harvey who criticized other anatomists harshlyin DeMotu Cordis, for trying to understand the heart and the circulationby dissecting only human cadavers—to the exclusion of comparativestudies and vivisection. Why does Harvey call this approach to under-standing the heart’s (and any other organ’s) motus proprius the rule ofSocrates? The Socratic method, also called the method of maieutike(Gk. for midwifery), involves interrogating others so as to be able to“bring out,” as it were, the truth by stimulating critical thinking in theanalysis of many alternate available viewpoints. Harvey suggests it asa method of getting at knowledge by experimentally (including animalvivisection) looking directly at the structure and function of parts or or-gans ofmany different species and at different ontogenetic stages, i.e., at


different developmental stages. To comply with his Socratis regula, in-vestigators should look for patterns of variation in structure and func-tion in order to determine what is essential to, e.g., a heart being aheart. That is, the investigator studies not just what an organ does in aspecific subject, or even in all members of its species, but, rather, whatthis organ’s purpose is in all species that have it.

6. The archetypes of Aristotle and Plato in Harvey’s analogies

O Aristotle! if you had had the advantage of being “the freshest modern”instead of the greatest ancient, would you not have mingled your praiseof metaphorical speech, as a sign of high intelligence, with a lamentationthat intelligence so rarely shows itself in speechwithoutmetaphor,—thatwe can so seldomdeclarewhat a thing is, except by saying it is somethingelse?—George Eliot, The Mill on the Floss, 1860 (Dover Giant ThriftEditions, 2003)

Beyond adhering to his rule of Socrates, Harvey also insisted on con-sideration of distant-domain observations, meaning beyond animalsand beyond functional anatomy. As he elaborated, distant-domainanalogies – linking together far-flungdomains of knowledge –might re-late to the deeper truths of nature, or serve to reject mistaken ideaswhen dealing with challenging problems, or help discern the functionsof bodily organs. Analogy and metaphors, or similes, are also parts ofAristotle's Rhetoric, which even today is considered by most expertsas the most important single work on persuasion ever written [18,19].Harvey studied rhetoric at The King’s School, Canterbury, which is fre-quently described as the oldest grammar school in England, probablyestablished by St. Augustine in 597. At King’s School, Harvey acquiredLatin, and perhaps Greek, and at 16 years of age was admitted at CaiusCollege, Cambridge, where the undergraduate curriculum comprisedscholastic dialectic, philosophy, and rhetoric [20]. Many arguments inDe Motu Cordis are rhetoric, typically Harvey’s examples and his analo-gies and similes; he esteemed metaphors and similes as not whimsicalbut as disciplined observations. They had to be apposite, correspondingrationally to what was signified.

7. The creative power of an apt proportional or analogical metaphor

It is evident from his quotations of Aristotle that Harvey had studiedhim systematically. It is not surprising that the Aristotelian Harvey’s DeMotu Cordis skillfully employed not only rigorous anatomical methodsbut also rational rhetorical ways of comparison, involving analogies,both near and distant. In distant-domain analogy, target and sourcecome from widely diverging provinces; as Aristotle taught [18], thiskind of metaphor is created on the basis of innate similarity: you haveto grasp the similarity in things that are apart. An analogy will oftendemonstrate how two entities or phenomena are alike by their sharedcharacteristics, suggesting that if they are comparable in some ways,they are similar in other ways as well. In a recent publication [3], Ihave discussed in some detail Harvey's use of a resonant distant-domain analogy, in which the circulation of the blood is compared inchapter VIII ofDeMotu Cordis to the greatwater cycle of themacrocosmthat Aristotle himself had described in hisMeteorologica. It is convincingbecause the relationships on one side match up with the relationshipson the other; across both sides there is rotation (viz., of planets/blood)around a central entity (sun/heart).

Scientific thought not uncommonly employs distant-domain analo-gies, such as the snake analogy involving a dream image of a snake thatsnatched its own tail in its mouth, giving August Kekulé the notion forthe benzene ring [21], or Ernest Rutherford’s comparison between thestructure of our solar system and that of an atom [22]. Similarly, whenGalileo wanted to transcend the geocentric Ptolemaic system with theunfamiliar Sun-centered world of Copernicus, he invoked an analogy




between the Sun-centered solar system of planets and Jupiter’s systemof moons, the four most massive of which – Ganymede, Callisto, Io,and Europa – could be directly observed through his 30×magnificationtelescope [23].

Aristotle and Plato (see Fig. 1), whomHarvey venerated besides “thedivine Galen” [2,3,24], were both fervent defenders of analogy, seeing itas a fertile medium for thinking. Nonetheless, they both felt compelledto point out its limitations; e.g., in the Sophist we are told by Plato [25]that, when used ill-advisedly, analogies are “most slippery things,” lia-ble to mislead both those who utter them and those who hear them.Harvey’s mind dared to explore highly far-fetched but insightful con-nections between distant-domain concepts—to be more precise, do-mains that seem distant only on the surface.

8. Harvey’s mechanical analogies for grasping swift coordinatedatrioventricular function

Harvey seems to have been naturally predisposed to draw inspira-tion from analogy between particular confusing observation(s) to beexplained or expounded and carefully chosen, already familiar phenom-ena. Consider, e.g., the following excerpt from chapter V of De MotuCordis describing the action and function of cardiac motion [11]:“These two motions, one of the ventricles, the other of the auricles,take place consecutively, but in such a manner that there is a kind ofharmony or rhythm preserved between them, the two concurring in

Fig. 1. Central detail from La Scuola di Atene (1509–1510), The School of Athens, a frescopainting (painting done in sections on smooth, fresh plaster) by Raphael (1483–1520)on one of the four walls of the room (stanza in Italian is a public room or resting place)named the Stanza della Segnatura, in the Vatican palace. At the center of the picture arePlato, pointing up to his Ideal Forms in heaven, and Aristotle, gesturing down to the RealWorld here on earth. Their identities are unambiguous, because each carries one of hisown famous books, clearly labeled. But these are hardly necessary: Raphael has capturedthe essence of the two great men’s philosophies, in promptly legible form, simply in theirgestures!


such wise that but one motion is apparent, especially in the warmerblooded animals, in which the movements in question are rapid. Noris this for any other reason than it is in a piece of machinery, in which,though one wheel gives motion to another, yet all the wheels seem tomove simultaneously (see Fig. 2); or in that mechanical contrivancewhich is adapted to firearms, where, the trigger being touched, downcomes the flint, strikes against the steel, elicits a spark, which fallingamong the powder, ignites it, when theflame extends, enters the barrel,causes the explosion, propels the ball, and the mark is attained (seeFig. 2)—all of which incidents, by reason of the celerity with whichthey happen, seem to take place in the twinkling of an eye: Omnes istimotus, propter celeritatem, quasi in nictu oculi simul fieri apparent. Soalso in deglutition … Even so does it come to pass with the motionsand action of theheart, which constitute a kindof deglutition, a transfer-ence of the blood from the veins to the arteries.”

The preceding flintlock mechanism for exploding the gunpowder ofa firearm, elsewhere the filling of leather satchels or bags, or the passageof blood past valves acting like those gates or sluices bywhich themoveforward of rivers is stopped, andnumerous other conjured images: all ofHarvey’s analogies invoke familiar concepts and impart tangible, me-chanical attributes to the circulation of the blood. Because of the unifor-mity of human minds, moreover, the novel concepts that are beingpresented byHarvey (whichmay be puzzling at first glance) become in-telligible as we relate them to our own prior experiences through theanalogies and metaphors that he invokes. Indeed, the spotting of analo-gies and analogy making was a central tactic behind both the discoveryand the presentation of the pulsating heartbeat and the circulation.

9. Harvey’s concept of the circulationof theblood:DeMotu Sanguinis

Harvey envisioned the circulation as consisting of two partial cyclesor loops [3]. In one, the greater or systemic loop, the left ventricle pumpsblood out of the heart to pass through the aorta into the main system ofarteries, returning to the heart through the venous system, and thereentering the right auricle. In the other, the lesser or pulmonary loop,the right ventricle pumps out blood through the pulmonary artery andon into the lungs, to return via the pulmonary vein(s) to the left auricle.Thus, the heart produces the complete circulation by means of two au-ricles and two ventricles, not by two ventricles alone.

Right at the outset, in the Proemiumof Exercitatio Anatomica deMotuCordis et Sanguinis in AnimalibusHarvey draws amicrocosm–macrocosmanalogy between the circulatory system as conceived by himself and thewater–weather cycle as formulated by Aristotle [3]. This distant-domainanalogy may have been of crucial importance for Harvey’s repositioningaway from the well-trodden path of Galenism. It enabled Harvey to un-derstand the reversible metamorphosis affecting the two types of blood,venous and arterial. Whereas this transmutation did not pose a problemfor adherents to Galen who understood circulation predominantlythrough vitalistic interpretations, it caused a conundrum for Harveywho had to rationalize the continuous interconversion of the twotypes of blood. From what was known at that time about blood and itsfunction, Harvey was unable to account for this in a causal, mechanisticsense. However, the Aristotelian water–weather cycle provided himwith a germane, putative analogy, so that his circulation schema exhibitsan aura of causality.

Specifically, in Aristotle’s first book of Meteorologica [26], cyclicalqualitative shifts from water into vapor and vapor into water couldarise out of alternating evaporation and condensation. Just as the Sunplays a causal role in this process in the familiar Aristotelian sourceanalog, so too the heart converts the blood by thrusting it through thelungs in the unfamiliar Harveian target analog. This distant-domainanalogy allowed a closed system for circulation of bright arterial anddark venous blood (whereas Galen’s paradigm, in which the bodily tis-sues continuously consumed the blood, entailed an open system). Theanalogy fromAristotelianmeteorological physics enabledHarvey’s pen-etrating conceptual insight and his epoch-making discovery of the



Fig. 2. Right top inset: Gears were invented by the Greek engineers of Alexandria in the third century BCE and were substantively perfected by the great Archimedes (287–212 BCE); theycould be of extraordinary sophistication andbecame theprototypes of allmodern-day gearing. The input gear, or drive gear, transmits power to the output, or driven, gear(s), which are setrotating instantaneously in opposite sense to the drive gear.Main panel:A firearmflintlockmechanismhas a piece offlintwhich is held in place by a set of jaws on a hammer. The hammeris pulled back into the “cocked” position. When released by the trigger, the spring-loaded hammer rotates forward, causing the flint to strike the steel; this pushes the steel back, whichopens the cover to the pan, which contains a small quantity of priming gunpowder. As the flint strikes the steel it creates a spark of burning metal, which falls into the exposed pan andignites the priming powder; fire burns through the touch-hole, a tiny pinhole into the barrel adjacent to the pan, and ignites the main powder charge, causing the gun to fire. The entireprocess appears to unfold quasi-instantaneously.


circulation of the blood. An unparalleled revolution in physiologicalthinking ensued [3]. Creativity is critical to science! By using Aristotle’swater cycle analogy, Harveywas able to handle the enigmatic feature ofthe circulation posed by the cyclic interconversion of the venous and ar-terial circulating blood.

10. The cyclic interconversion of venous and arterial circulating blood

Eventually, the enigma of the cyclic interconversion of the venousand arterial circulating blood was explicated dispositively. It was in1667 that Richard Lower and Robert Hooke began to collaborate on car-diopulmonary investigations and, on Hooke's suggestion, sought to de-termine experimentally the exact effect on the blood of its passagethrough the lungs. A period of concentrated experimentation and con-ceptualization led to the publication of Lower’s Tractatus De Corde[27,28], in which he asserted that just its sheer exposure to the air inthe lungs altered the blood's color.Whereas blood still appeared venousas it left the right ventricle, it had already become arterial as it advancedfrom the lungs to the left ventricle. Accordingly, the shift from the bur-gundy shade of venous to the bright, crimson color of arterial bloodwas“entirely due to the penetration of particles of fresh air into the blood”[29], in its passage through the lungs. Parenthetically, it is worth noting


that Erasistratus (304–250 BCE), who may have been the grandson ofAristotle by his daughter Pythias, who was born on the Aegean islandof Chios in Greece and is considered the founder of Physiology, had al-ready suggested 19 centuries earlier that air drawn in through thelungs somehow combined with blood [29].

11. Harvey’s conception of the cardiac function: De Motu Cordis

In many of his works, Aristotle had established different aspects of atight link between a thing’s form, its function, and the characteristic ac-tivities thatmake it what it is [30]. The rational cause, or logos, of a bodi-ly part or organ is what it is to be that part, i.e., its function; a functionunderstood as entelechy, the actuality inhering in a telos that manifestsan intention in the organ’s physiological structure. Harvey studied car-diovascular structures with the ultimate goal of producing a generalsynthesis inwhich the functioning of every structure or organ, includingthe heart, would become known in relation to its form and structure, sothat its activities, as part of the performance of the body as a livingwhole, could be understood in the Aristotelian sense.

There has been considerable disagreement as to the importance ofmodern-day mechanical reasoning in Harvey's work, and its relevanceto the discovery of the circulation [3,31–33]. Central to the debate is




the paradigm of the heart as a pump, which was first mentioned inHarvey's Prelectiones [13,14], lecture notes prepared simply for Harvey’sown usewhile conducting didactic dissections as the Lumleian Lecturerat the College of Physicians in London, in the second decade of the 17thcentury—initially, in 1616. De Motu Cordis was first published in 1628.

The relationships on either side of this specific analogy involve suchconcepts as output, pressure, suction, compression, and so forth. Theanalogy is palpably convincing exactly because the relationships onone side match up with those on the other. Actually this insightfuldistant-domain analogy was not new: Erasistratus had implicitly laidthe foundations of the theory of themotion of the blood [2,3]. He recog-nized that the heart served as a mechanical pump distending the arter-ies to produce a pulse with each stroke, much as one can fill a bladderwith air by blowing into it. That is, he assigned a passive role to the ar-teries, and he understood and described the functioning of the heartvalves. Unfortunately, all his works are lost. We have only episodic indi-rect accounts of his accomplishments through fragmentary referencesto him in the works of his successors, primarily Galen [3,34].

12. Comparison of the heart to a bellows, a mechanical pump

Galen had compared the action of the heart to that of a pair ofblacksmith's bellows [35], both possessing an attractive (suction) forceby virtue of nature's general aversion to a vacuum, as formulated byAristotle, to explain why water rises in a bellows or a siphon. The tradi-tional bellows,whichwas applied to fireplace use inmost households inEngland at Harvey's time, approximates a two-valve pump by havingthe resistance to backflow through the effluent nozzle being muchhigher than that through the inflow orifice. Towit, fluid flows into a bel-lows pumpvia the inlet valve as the cavity expands and it thenflows outthrough the nozzle –which may have a unidirectional outflow valve tostop burning particles from the fire from being sucked back into thebellows – as the cavity collapses. Harvey must have seen many typesof bellows pumps, and drawings of such, as a medical student inPadua between 1599 and 1602 (see Fig. 3).

Harvey envisaged the mechanical function of the heart as a positivedisplacement pump. Some positive displacement pumps employ anexpanding cavity in the suction phase and a decreasing cavity in the dis-charge phase. Accordingly, in his Prelectiones, Harvey maintains that[13,14] “From the structure of the heart, it is clear that the blood is con-stantly carried through the lungs into the aorta as by two clackes of awater bellows to rayse water (sic). It is certain from the experiment ofthe ligature (the test of venous filling, which is nowadays referred tosometimes as Harvey's sign) that there is a passage of the blood fromthe arteries to the veins. And for this reason it is certain that the perpet-ualmovement of the blood in a circle is caused by theheartbeat.”Harveyexplained the “two-clack” system in his Lumleian Lectures of 1616.

The Prelectiones, or Lecture Notes [13,14], are in the main written inLatin, but sporadically, words and phrases such as the above italicizedanalogy are in English, a characteristic of Harvey’s spontaneity in his in-formal writings. The Mysteries of Nature and Art, by John Bate, is an in-triguing technical compendium published in London in 1634. Many ofBate's hydraulic devices are taken fromworks of the ancient Hellenisticengineers [36]. Bates describes a clack(e) as “A peece of leather nayledover any hole, having a peece of lead to make it lie close, so that theayre or water in any vessell may thereby bee (sic) kept from goingout” [37]. Accordingly, Harvey is describing a pumpwith onewayvalves(see Fig. 3), with properties of both sucking and forcing. The forcingphase is intuitively obvious; the sucking phase can be understood bythinking of a syringe analogy: When the orifice of a syringe is insertedinto a container of liquid and the piston drawn up, the air having noway to enter the vacuum thus formed than by the small orifice underthe surface of the liquid, presses the water before it into the body ofthe syringe.

Harvey's water bellows may have been the fire-engine pump, intro-duced in England in 1625 [32]. In a letter of 1649 addressed to Jean


Riolan, who in 1648 in his Encheiridium Anatomicum had published arival theory to Harvey’s circulation, Harvey used a comparable analogy:“Whenwater is forced up to a height through leadpipes by the force andstroke of afire engine,we are able to distinguish and observe a sequenceof events in the selfsame outflow of water (even if this is many stagesdistant) at each compression of the instrument. At each stroke there isa beginning, increase, climax and vehemence and so it is at the openingof a split artery” [38].

Harvey used themechanistic language of the pump technology of histime in explicating his radical central idea that the heart is a pump. As Iobserved in the context of Fig. 2 earlier, he also described the heart asbeing analogous to an intricate piece of machinery in which one cog-wheel imparts motion to another. When one considers that Harveycould think and write in these terms in the Galenic Medicine dominatedintellectual environment of his times, his is a truly astoundingattainment!

As we have seen repeatedly already, Harvey used a variety of analo-gies, in the pattern set by Aristotle and Plato, to reason about the circu-lation. Indeed, I am struck by the manner in which the evolution of theideas of De Motu Cordis et Sanguinis entails a series of snowballing anal-ogies. These were often from the domains of Mechanics or Physics,which allowed Harvey to understand and formulate plainly various so-phisticated cardiovascular functions. In his Lectures to the College ofPhysicians [13,14], he compared, e.g., the mechanism of an erection tothe inflation of a glove – reminiscent of Erasistratus’ notion regardingthe generation of the arterial pulse – and he likened the working ofthe lungs and thoracic walls including the diaphragm to a bladderwith-in a pair of bellows!

13. Harvey’s reveals systolic contraction as the motus proprius ofthe heart

In Harvey's De Motu Cordis, the heart acts like a suction pump, firstsucking in and then pumping out the life blood of the organism in a per-petual circulation. We are undoubtedly impressed with the clarity andfinality of Harvey's proofs of his views. In De Motu Cordis, he assembles,one by one, the elements of confirming evidence that the heart ispumping blood and that there is a correlation between the systole anddiastole of the pulse in the arteries and the contractions and dilationsof the heart; that the apical thrust (as felt at the point of maximal im-pulse on the chest) corresponds to systolic contraction; that the bloodflows from the heart peripherally through the arteries and centripetallytoward the heart through the veins; and that the valves in the veins per-mit unidirectional flow of blood, only toward the heart. In the followingexcerpts, I have complied with the translation of Harvey’s De MotuCordis created by Robert Willis (1799–1878) [11], which is valued asthe standard English language rendering.

14. Cardiac vivisectionderived observations conflictingwith acceptedGalenic doctrine

In chapter II ofDeMotu Cordis, Harvey infers, “From these particularsit appears evident tome that themotion of theheart consists in a certainuniversal tension—both contraction in the line of its fibres, and constric-tion in every sense. It becomes erect, hard, and of diminished size duringits action; themotion is plainly of the same nature as that of themuscleswhen they contract in the line of their sinews and fibres; for the mus-cles, when in action, acquire vigor and tenseness, and from soft becomehard, prominent, and thickened: and in the same manner the heart.

We are therefore authorized to conclude that the heart, at the mo-ment of its action, is at once constricted on all sides, rendered thickerin its parietes and smaller in its ventricles, and so made apt to projector expel its charge of blood. This, indeed, is made sufficiently manifestby the preceding fourth observation in which we have seen that theheart, by squeezing out the blood that it contains, becomes paler, andthen when it sinks into repose and the ventricle is filled anew with



Fig. 3. Left panels: Bellows is in essence a chamber that can be alternatingly expanded and contracted by an external force, such as applied simply by hand or assisted by various weighted-bearing contraptions. On one side of the chamber is an inlet or “suction” valve that allows fluid in but not out.When the chamber is expanded, fluid is drawn in through this valve to fill upthe partial vacuumproduced;when the chamber is contracted, the inlet valve is closed by the fluid attempting to rush out again and the fluid is forced out through the nozzle, whichmayhave a unidirectional outflow or “delivery” valve; this stops, e.g., burning coal particles from a forge from being sucked back into the bellows. Bellows are intended for the transfer of largequantities of fluids at low relative pressures, very little above that of the atmosphere. Right panel: Multicompartment, compound bellows can maintain a more continuous fluid current,rather than the intermittent puffs necessitated by the interval required to refill the chamber of a simple bellows after each discharge [Adapted from a drawing inNovo Teatro di Machine etEdificii by Vittorio Zonca (1568–1603), published in Padua in 1607, by courtesy of the Archimedes Project of the Max Planck Institute for the History of Science (MPIWG), Berlin].


blood, that the deeper crimson colour returns. But no one need remainin doubt of the fact, for if the ventricle be pierced the blood will be seento be forcibly projected outwards upon each motion or pulsation whenthe heart is tense. These things, therefore, happen together or at thesame instant: the tension of the heart, the pulse of its apex, which isfelt externally by its striking against the chest, the thickening of itsparietes, and the forcible expulsion of the blood it contains by the con-striction of its ventricles.

Hence the very opposite of the opinions commonly received appearsto be true; inasmuch as it is generally believed that when the heartstrikes the breast and the pulse is felt without, the heart is dilated inits ventricles and is filled with blood; but the contrary of this is thefact, and the heart, when it contracts (and the impulse of the apex isconveyed through the chest wall), is emptied. Whence the motionwhich is generally regarded as the diastole of the heart, is in truth itssystole. And in like manner the intrinsic motion of the heart is not thediastole but the systole; (Et similiter motus proprius cordis Diastole nonest, sed Systole;) neither is it in the diastole that the heart grows firm


and tense, but in the systole, for then only, when tense, is it movedand made vigorous.” Thus, Harvey asserts that the motus proprius ofthe heart, its quintessential action as an organ in the Galenic sense, isnot diastole but systole!

15. The arterial pulse results from the systolic impact of ejectedblood–ab impulsu sanguinis

In chapter III of De Motu Cordis, he submits further that “At the mo-ment the heart contracts, and when the breast is struck, when in shortthe organ is in its state of systole, the arteries are dilated, yield a pulse,and are in the state of diastole. In like manner, when the right ventriclecontracts and propels its charge of blood, the pulmonary artery isdistended at the same time with the other arteries of the body.

When the left ventricle ceases to act, to contract, to pulsate, the pulsein the arteries also ceases; further, when this ventricle contracts lan-guidly, the pulse in the arteries is scarcely perceptible. In like manner,the pulse in the right ventricle failing, the pulse in the pulmonary artery




ceases also. Further, when an artery is divided or punctured, the blood isseen to be forcibly propelled from the wound the moment the left ven-tricle contracts; and, again, when the pulmonary artery is wounded, theblood will be seen spouting forth with violence at the instant when theright ventricle contracts… Finally, that the pulses of the arteries are dueto the impulses of the blood from the left ventricle, may be illustrated byblowing into a glove, when thewhole of the fingers will be found to be-come distended at one and the same time, and in their tension to bearsome resemblance to the pulse … Whence it appears that wheneverthe motion of the blood through the arteries is impeded, whether it beby compression or infarction, or interception, there do the remote divi-sions of the arteries beat less forcibly, seeing that the pulse of the arter-ies is nothing more than the impulse or shock of the blood in thesevessels.”

From his detailed inspections of the heartbeat, Harvey deduced thatthe proximal arterial trunksmust expandwhen the heart contracts; andwith his instructive glove analogy, he made his point convincingly [39].At this juncture, I note again that Erasistratus too had assigned a passiverole to the arteries: he had argued that the heart worked mechanically,filling the arteries with pneuma, which resulted in a dilation or pulse,akin towhen onefills a bladderwith air by blowing into it. In agreementwith Erasistratus' account of the passive role of the arteries, Harveyshowed that the pulse is not carried as an active wave of expansionalong the arterial coats.

Realdo Colombo's observations of the heart [3] had enabled him tooto gain a more correct understanding of the phases of the heartbeat,which had been generally confused by his predecessors; they errone-ously categorized the motus proprius of the heart as akin to the expan-sive action of a bellows. Although overshadowed by his work on thepulmonary circuit [3], Colombo's observations of the heartbeatwere de-scribed in his De Re Anatomica Libri XV, published in Venice, in 1559;they apparently directly inspired Harvey's vivisectional studies on theheart, which in turn led to his discovery of the circulation.

16. Some Harveian structure–function correlations

In chapter XVII, Harvey expounds further: “For the same reason thepulmonary artery not only has the structure of an artery, but it does notdiffer so widely from the veins in the thickness of its walls as does theaorta. The aorta sustains a more powerful shock from the left than thepulmonary artery does from the right ventricle, and the walls of thislast vessel are thinner and softer than those of the aorta in the same pro-portion as the walls of the right ventricle of the heart are weaker andthinner than those of the left ventricle. In like manner the lungs aresofter and laxer in structure than the flesh and other constituents ofthe body, and in a similar way the walls of the branches of the pulmo-nary artery differ from those of the vessels derived from the aorta.”

17. Harvey’s intuitive understanding of cardiac unsteadyfluid dynamics

Some reflection of the preceding passages cannot but fill today’shemodynamicists and cardiac fluid dynamicists with awe and admira-tion of Harvey’s insights, deriving from countless hours of thoughtfulexperimentation; these encompassed animal vivisection eliciting ahyperadrenergic state, without sedation or anesthesia that can depressventricular dynamics substantially [40,41]. Words such as “the impulseor shock” of the blood in the aorta and the pulmonary artery and the as-sertion that “the aorta sustains amore powerful shock from the left thanthe pulmonary artery does from the right ventricle” sound surprisinglymodern [42,43]. This, however, should not cause us to lose sight of thefact that, when De Motu Cordis was published in 1628, Isaac Newton(1642–1727) had not been born and understanding of impulsive forcesand the impulse-momentum theorem [42,43], which is logically equiv-alent to Newton's second law of motion, were still concealed well intothe future—Newton’s Principia Mathematica was published in 1687.


18. The function of the auricles

In chapter IV, Harvey elaborates, “And here I would observe, thatwhenever I speak of pulsations as occurring in the auricles or ventricles,I mean contractions: first the auricles contract, and subsequently theheart itself contracts. When the auricles contract they are seen to be-come whiter, especially where they contain but little blood; but theyare filled asmagazines or reservoirs of the blood, which is tending spon-taneously and, by its motion in the veins, under pressure towards thecentre; the whiteness indicated is most conspicuous towards the ex-tremities or edges of the auricles at the time of their contractions.”

19. Purpose and function of the unidirectional cardiac valves

In chapter VII, Harvey invokes the cogent explanation of the need forthe cardiac valves, which is found in Galen’s De Usu Partium, Lib. VI, Cap.10 and 11: “The same fact he (Galen) has also alluded to in a precedingpart of the tenth chapter: “Were there no valves, a three-fold inconve-nience would result, so that the blood would then perform this length-ened course in vain; it would flow inwards during the diastoles of thelungs and fill all their arteries; but in the systoles, in the manner of thetide, it would ever and anon, like the Euripus, flow backwards and for-wards by the same way, with a reciprocating motion, which would no-wise suit the blood.”

The Euripus Strait is a narrow water channel separating the Aegeanisland of Euboea fromBoeotia in Central Greece. It is subject to extreme-ly violent tidal currents reversing direction approximately four times aday. Tides are generally very weak in the Eastern Mediterranean, soEuripus is the extraordinary exception. Sea water speeds peak atabout 8 miles/hour, northward or southward, and underpowered ves-sels are commonly incapable of sailing against the current. Whennearing flow reversal, the setting is even more hazardous because ofpowerful vortex formation. In his Phaedo, Plato has Socrates use theEuripus tide as a simile for things that “go up and down,” in describingthe thinking of those who hold that nothing is sound or stable.

Harvey agrees with Galen that this flow, “backwards and forwardsby the same way,”may seem a matter of little moment, “but if it mean-time appear that the function of respiration suffer as a result, then[Galen thinks] it would be looked upon as no trifle, etc. … From Galen,however, that great man, that father of physicians, it clearly appearsthat the blood passes through the lungs from the pulmonary arteryinto the minute branches of the pulmonary veins, urged to this bothby the pulses of the heart and by the motions of the lungs and thorax;that the heart, moreover, is incessantly receiving and expelling theblood by and from its ventricles, as from a magazine or cistern, and forthis end it is furnished with four sets of valves, two serving for the in-duction and two for the education of the blood, lest, like the Euripus, itshould be incommodiously sent hither and thither, or flow back intothe cavity which it should have quitted, or quit the part where itspresencewas required, and so the heartmight be oppressedwith labourin vain, and the office of the lungs be interfered with.”

20. Functional anatomy of cardiac walls, myocardial mechanics, andlive integrated atrioventricular performance

In chapter XVII, Harvey describes papillary muscles, trabeculaecarneae, and chordae tendineae and their role in systolic contractionand the emptying of the ventricular chambers: “There are, moreover,within the heart numerous braces, in the form of fleshy columns and fi-brous bands, which Aristotle, in ‘De Respirat.,’ and ‘De Part. Animal.’ bookIII, calls sinews. These are variously extended, and are either distinct orcontained in grooves in thewalls and partition,where they occasion nu-merous pits or depressions. They constitute a kind of small muscles,which are superadded and supplementary to the heart, assisting it toexecute a more powerful and perfect contraction, and so proving sub-servient to the complete expulsion of the blood. They are, in some




sort, like the elaborate and artful arrangement of ropes in a ship, bracingthe heart on every side as it contracts, and so enabling it more effectual-ly and forcibly to expel the charge of blood from its ventricles. Thismuchis plain, at all events, that in some animals they are less stronglymarkedthan in others; and, in all that have them, they are more numerous andstronger in the left than in the right ventricle; and while some havethem present in the left, yet they are absent in the right ventricle. Inman they are more numerous in the left than in the right ventricle,more abundant in the ventricles than in the auricles; and occasionallythere appear to be none present in the auricles. They are numerous inthe large, more muscular and hardier bodies of country men, butfewer in more slender frames and in females.” Some concepts thatHarvey presents in this passage are amazingly forward thinking! Theyinclude the role of the papillary muscles and the trabeculae carneae,which work through their systolic thickening to form pads of musclethat block off the ventricular lumen like bolsters, thus allowing morecomplete biventricular chamber emptying (see Fig. 4).

Little further on in chapter XVII, Harvey elaborates, “The auricles areprimemovers of the blood, especially the right auricle, which, as alreadysaid, is ‘the first to live, the last to die’; whence they are subservient tosending the blood into the ventricles, which, contracting continuously,more readily and forcibly expel the blood already in motion; just asthe ballplayer can strike the ball more forcibly and further if he takesit on the rebound than if he simply threw it. Moreover, and contraryto the general opinion, neither the heart nor anything else can dilateor distend itself so as to drawanything into its cavity during thediastole,unless, like a sponge, it has been first compressed and is returning to itsprimary condition (nisi ut spongia ui prius compressa, dum redit adconstitutionem suam).” As I have emphasized elsewhere [3,42], thismode of application of a kind of sucking action (“vis a fronte”) by themyocardium in rebounding in diastole from a systolicmyocardial defor-mation yielding an end-systolic chamber volume lower than the so-called unstressed volume is a strikingly modern conception [44–46]. Itbetrays amazing insight born out of countless hours of thoughtfulexperimentation.

Continuing, he states, “But in animals all localmotion proceeds from,and has its origin in, the contraction of some part; consequently it is bythe contraction of the auricles that the blood is thrown into the ventri-cles, as I have already shown, and from there, by the contraction of theventricles, it is propelled and distributed. Concerning local motions, itis true that the immediate moving organ in every motion of an animalprimarily endowed with a motive spirit (as Aristotle says in his bookDe Spiritu and elsewhere), is contractile… if I am permitted to proceedin my purpose of making a particular demonstration of the organs ofmotion in animals from observations in my possession, I trust I shall

Fig. 4. The papillary muscles and the trabeculae carneae work through their systolic thickening tcomplete emptying and the attainment of low end-systolic blood volumes; apm = anterior andpventricle; EDV = end-diastolic and ESV = end-systolic volume. (Adapted and modified from P


be able to make sufficiently plain how Aristotle was acquainted withthe muscles, and advisedly referred all motion in animals to the nerves,or to the contractile element.”

21. The heart as a muscle–myocardial fiber structure and function

Harvey emphasizes in chapter XVII of De Motu Cordis that “it is notwithout good grounds that Hippocrates in his book, De Corde, entitlesit [the heart] a muscle; its action is the same; so is its functions, viz., tocontract andmove something else—in this case the charge of the blood.”

He continues his exposition of the heart as amuscle, as follows: “Far-ther, we can infer the action and use of the heart from the arrangementof its fibres and its general structures, as in muscles generally. All anato-mists admit with Galen that the body of the heart is made up of variouscourses of fibres running straight, obliquely, and transversely, with ref-erence to one another; but in a heartwhich has been boiled, the arrange-ment of thefibres is seen to be different. All thefibres in the parietes andseptum are circular, as in the sphincters; those, again, which are in thecolumns (our papillarymuscles) extend lengthwise, andare oblique lon-gitudinally; and so it comes to pass that when all the fibres contract si-multaneously, the apex of the cone is pulled towards its base by thecolumns, the walls are drawn circularly together into a globe–thewhole heart, in short, is contracted and the ventricles narrowed. It is,therefore, impossible not to perceive that, as the action of the organ isso plainly contraction, its function is to propel the blood into the arter-ies.” What a marvelous understanding of cardiac mechanics!

22. Conclusion

William Harvey worked as a tireless and thoughtful experimenterand a transmitter and intermediary between the ancient Greek naturalphilosophers and physicians and the “moderns,” for whom he foundedtwo forward-looking sciences: modern Physiology and nascent cardiol-ogy. Harvey's methodology and demonstrations were of such funda-mental and standardizing nature as to secure the sure progress ofthese two sciences. If Harvey disproved Galen, he absorbed and contin-ued in his physiologic researchmany a principle from Aristotle. The au-thority of Aristotlewas strongwith him to the end—“always he has suchweight with me,” he wrote in his old age of Aristotle [47], “that I neverthink of differing from him inconsiderately.” Harvey's account of themotions of the heart and blood demonstrated that they can be repre-sented in straightforward mechanical terms, a concept which hasremained fundamental to the present day.

Mechanistic medicine (“Iatromechanics”), which saw the body as amachine, was developed further in the second half of the 17th century.

o form pads of muscle that block off the ventricular lumen like bolsters, thus allowingmorepm = posterior papillarymuscle; ivs = interventricular septum; lv = left and rv = rightasipoularides [42], with permission of PMPH-USA.)




A philosophical implication of Harvey’s discovery of the circulation wasthe resolute application of the experimental method to cardiology. Inmy judgment, he established today’s forward-looking discipline oftranslational cardiovascular research. In due course, he should be wide-ly acknowledged to have done so. His work embodies magnificently theconcept epitomized in Heraclitus frag. 55 [1]: Whatsoever things (are)objects of sight, hearing, (and) experience—these things I hold in higheresteem! Quite fittingly, then, Abraham Cowley (1618–1667), an Englishpoet widely considered in his own time to be the greatest poet of theage, wrote in his “Ode upon Dr. Harvey” (1657) [6]:

Harvey sought for truth in Truth's own bookCreation—which by God himself was writ;And wisely thought 'twas fitNot to read comments only upon it,But on th' original itself to look.

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greek underpinnings to his methodology in unraveling de motu cordis and what harvey has to teach us...

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