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I. Introduction - II. From ancient cardiological beliefs to the “weighing” of the heart - III. The heart in Holy Scripture - IV. The heart from Hippocrates to Harvey - V. The heart in modern experimental medicine.

I. Introduction

For millennia the fascinating enigma of the unceasing beating of the heart has been a source of unexhausted stupor, wonder and veneration. Humans have often wondered what the mysterious force of the living principle was that keeps the heart in constant motion and makes it possible for it never to stop beating throughout the duration of an individual’s lifetime. It was immediately clear that it certainly had to be a force linked to the dynamics of life’s preservation, because it lasts as long as the heart beats, whereas the heart’s arrest immediately brings about the end of all the organism’s other movements, i.e. the individual’s physical death. It is not by accident that, since the earliest times, the focus of the most fascinating issue of biology, i.e. the enigmatic and stunning ability of the organism to preserve itself from death and to stay alive for relatively long periods of time, had been the unceasing beating of the heart.

A knowledge of the acting mechanisms of the energy that produces the unceasing rhythmical beat of the heart was held to be indispensable to understand life in general, and its distinctive features in particular. It had been apparent since Antiquity that the discriminating threshold between the living and the non-living realms, was that the living matter — as Schrödinger (1948) repeated— “moves, trades materials with the environment and so on, and this happens over a much longer period than we would expect of a piece of inanimate matter under similar circumstances.” And it was precisely in this peculiar ability of an organism to keep itself fit over a long period that magicians, astrologers, priests and physicians in Antiquity saw life’s truly mysterious side. The whole ancient biological thought, even before and even more intensely than in Schrödinger’s emphatic terms, originated in the primary awareness that “it is precisely in its present avoidance of a rapid decay into a state of inertial ‘equilibrium’ that an organism looks so mysterious.” Since archaic times the unceasing beat of the heart appeared to be the most tangible manifestation of the utter depth of this mystery of life.

In as much as it is the seat and expression of an intrinsic conservative power, the heart soon turned into a synonym of life and its range of meanings was enriched with as many nuances and connotations as were the spirits, the types of souls and the living principles which were in turn employed when attempting to explain its unceasing movement. Through the ages the word “heart” underwent as many semantic shifts as were the astral circles, physical models and heavenly entities it was compared with, or related and assimilated to. Thanks to the complexity of its semantic network, the heart always exhibited a powerful metaphorical charge conveying mostly salvific symbols connected to the image of life’s continuous regeneration. It was the pivot of cultic notions, even prior to scientific and cultural, soteriological, anthropological and psychological understandings, religious beliefs, ethical precepts, medical teachings and dynamic-cosmological theories. The issue whether the heart be the centre or the organism’s first and hegemonic principles, and whether it should wield the supreme power over the organism itself has always been intertwined — in a thick network of analogies, derivations, intersections and mutual influences — with psychological and anthropological reflections and has been instrumental in defining the overall notion of man. It is not all surprising, therefore, that behind the fascinating history of ancient cardiology one may always glimpse the face of a human being who sees in his/her heart the embodiment of their own natural desire for continuous regeneration and of their overwhelming yearning for immortality.

II. From ancient cardiological beliefs to the “weighing” of the heart

As synonymous with life and regenerating power, the heart has been one of the main subjects of ritual and religious iconography of all peoples and ages. The first of the depictions we know dates back to a period ranging from fifteen- to ten-thousand years ago. It is a graffito at El Pidal, in the Asturias (Spain), which depicts the heart of a trunked animal (elephant or mammoth), a species which became extinct in the glacial era.

Despite its frequent representation since the crags graffiti of archaic times, the heart has not always been seen as the main organ and the primary  source of life. Blood, liver and brain have often competed with it for primacy, since humans have often attached greater value to those parts. Amongst the Sumerians, Assyrians and Babylonians, the peoples of the most advanced civilizations of the great river basin, blood-centred beliefs prevailed. Mesopotamian mythology not only offered a version of creation where humans would descend from a god’s blood mixed with clay, but it also assigned blood the absolutely primary function as the repository of magic forces and of the cosmic energies endowed with the power of keeping the organism alive through unceasing reactivation of the cyclical regeneration processes. Without the blood not only would life never have arisen, but it would not even have had the chance of surviving through time. Within this magic-mythological horizon, the word “blood” directly represented the mysterious power endowed with the ability to make beings endure over time. One could not therefore help resorting to the blood in all those cases in which long stability and endurance had to be guaranteed. Official agreements, for instance, became valid and unchangeable only if they were signed with blood. Similarly, shedding the blood of a sacrificial victim into a building’s foundations was held to be the only way of guaranteeing the duration of human edifices.

The complete equivalence between blood and life-keeping power was for Mesopotamian peoples the axiomatic foundation of their physiological liver-centred theory and of their firm trust in divinatory liver observation. The liver, held to be the hematopoietic organ par excellence, was assimilated to coagulated blood and so to a reservoir of concentrated life. Hence, it was the liver and not the heart – which was regarded as the seat of understanding – that was given a key role as the organism’s central engine, as a source of blood and the point from which veins originated. It was thus even too obvious that these premises would result in the unfailing conviction that health, fate, and life duration were inscribed from birth in the liver’s configuration, color and functional workings. The latter, preserved from any impurities – which themselves would only lie in the spleen – turned out to be the purest part of the body, hence the fittest to receive divine revelation. It was therefore natural to believe that with a meticulous scrutiny of the liver, the most delicate operation of all haruspices’ art, it was possible to directly find out about the will of the gods, every man’s future and, ultimately, the time left to live.

On the one hand, liver divination, a widespread practice amongst Eastern peoples as well as the Etruscans, was considered the first step of anatomy, but, on the other, it was based on assumptions which, from the strictly physiological point of view, assigned the heart a rather secondary role. Ancient Indian medicine made the heart the seat of the psychic activity and developed an interesting pulse doctrine, aimed at defining a sort of psychological characterisation based on a cosmic background and strongly interested in identifying the lunar or solar predispositions of the individual under scrutiny. Chinese medicine, in turn, numbered the heart within the class of male yang elements and resorted to a meticulous and painstaking ceremonial for the diagnosis of the various pulses, in order to measure the degree of harmony between the sounds transmitted by the twelve blood vessel systems.

It is in Egyptian medicine, though, that one finds what may regarded as the first recorded cardiology treatise. The most ancient cardiology document in history, datable to about 1500-1400 B.C., the Ebers Papyrus, named after the German scholar who discovered it at the end of the 19th century, reads: “Beginning of the physician’s secret: knowledge of heart motions and of the heart itself: in each limb there are vessels departing from it. Thus, when a physician, a surgeon or an exorcist place their hand and their fingers on head, back of the head, hands, stomach’s place, arms or feet, they are in fact scrutinizing the heart, because its vessels reach out to every limb: so it [the heart]  talks through each limb’s vessels.”

One should by no means underestimate the importance of this document for the history of cardiovascular notions, because, even though the vessels’ description is far from being accurate, the identification of the heart as the centre of the cardiovascular   system and the close correlation between heart and vessels pulse represent significant discoveries and remarkable steps forward. According to Egyptian physician-priests vessels do not only convey blood but also air, the living breath and all the other organic liquids: therefore, due to the very same origin of all vessels, tears, sperm and urine also flowed from the heart: “There are — we read in the Ebers Papyrus — four vessels in our nostrils, two producing mucus, two producing blood […].There are two vessels for testicles; it is them that produce seed […]. There are two vessels for the bladder: it is these that produce urine.”

As emerges from this brief description of the vascular system, the priests of ancient Egypt, who also played a role as physicians and exorcists, were more interested in the heart than in the flow of blood and of the other liquids within the organism. Although Egyptian medicine was essentially pneumatic (breathing was set at the foundations of life), the heart was held to be the organism’s most important and noblest part: “the heart of man — as it is written on a mummy case — is its own God.” Actually, the religious culture of ancient Egypt upheld a sort of firm “cardiolatry”, which would be echoed in the medical cultures of all the peoples of the Mediterranean basin and which would take on the role of an ancestral archetype to shape the physiological and anthropological doctrines of all Antiquity. The Egyptian priests-physicians held the heart – which in their view gained weight up to the age of fifty and gradually decreased later – to be the seat of understanding even before being that of emotions and feelings. “Eyesight — as the Ebers Papyruys says again, — hearing through the ears, breathing air through the nose all depend on the heart; it is the heart that judges and the tongue that proclaims what the heart has perceived.” Even god Path, according to Menphitic cosmogony, had conceived his project of creating of the world with his own heart. The centre of the vascular system, on the other hand, for ancient Egyptians was also the seat of the ab, that is the soul due to be weighed by the gods on the terrifying scale of the last judgment. Precisely because it was the inseparable dwelling of the ab, the heart of the deceased was obsessively looked after: it was either left in its place within the body of the deceased or it was removed and preserved in the canopies, the precious funeral vases with a head-shaped lid. Psychostasy, that is the weighing of the soul of the deceased carried out by the other world’s tribunal court in order to decide who would deserve the immortality of the blessed through their behavior, was no other than the weighing of the heart of the deceased. The heart was indeed regarded as the embodiment of the dead’s own intimate, deep conscience and therefore its most transparent and strictest witness. In the illustrations of psychostasy featured in many copies of the Book of the Dead, the deceased undergoes the judgment by the supreme court presided over by Osiris, assisted by as many as forty-two unflinching judges. His/Her heart is placed on the scale’s plate which on the other plate bears Maat, the ruthless divine pen tasked with writing the name of the deceased themselves. At the foot of the scale one sees the Devourer, a terrifying animal ready to tear the deceased apart, should they receive an unfavorable sentence.

To avoid the nightmare of a definitive annihilation in the Devourer’s open mouth one resorted to a funeral talisman the effectiveness of which was certain: a large “heart’s scrabble,” usually carved in hard stones, was placed where the mummy’s heart lay. On this scrabble’s flat side, the following ritual invocation was sculpted: “O heart of my most intimate essence! Do not turn against me as a witness before the court, because you are the god who is in my body, the creator who keeps all limbs alive.” Such an invocation was used to preventing the real heart from witnessing against the dead in the fatal moment of the psychostasy. The magical power and the indisputable practical effectiveness which magic-ritual formulas then prided themselves to have, were quite enough to guarantee the silence of the heart, an indispensable condition to attain salvation. Just like in all ages, also at that time the complete silencing of the heart, that is of the most intimate conscience, was regarded as the safest instrument human misery could avail itself of to deserve eternal life before the mercy of the gods.

If it is carefully analyzed, the scrabble symbolism discloses a network of analogical connections, which will be recur throughout the history of early cardiology until the 17th century. The peculiarity of that symbolism resides in placing the heart at the centre of a thick network of correspondences with the sun sole and at the centre of constant references to the notions of circle and cycle, of eternal return and of spontaneous regeneration. In fact, the reason why in funeral rites the scrabble (kheprer) took on the function of a surrogate of the heart, or of “magical heart,” lay in its special affinity with the Sun. The entire existence of the scrabble was actually interpreted as a perfect emulation of the venerable course of the Sun. Precisely because in its peculiar movement it followed the direction of the Sun, the scrabble was regarded as the manifestation of god Khepri, the rising sun which regenerates itself and rises again after every night. Just as the solar disc re-emerged from the abyssal darkness of the night, so too the scrabble was always reborn from the sphere constructed with the material of its own decomposition. In Egypt, as indeed Plutarch remarks, “the scrabble’s species is believed not to possess any female members, only male ones, who lay their seed into a sort of sphere-shaped substance they produce themselves and then roll down pushing it with their back paws, thus replicating the course of the Sun which in its movement from East to West seems to go in the opposite direction of that followed by the heavens.” The heart-scrabble, the most perfect emulation and manifestation of the Sun’s power on the Earth, nurtured a kind of cardiolatry by then conceived in terms of solar energies, magical circularities and of a perfect spherical shape within which the mystery of the complete regeneration of oneself is accomplished.

The most tragic and negative correlation between the heart and the Sun in the entire history of cardiological beliefs is still found, centuries apart, amongst the pre-Columbian Mesoamerican peoples and in particular amongst the Aztecs and the Mayas. For at least two millennia, from the 5th century B.C. until the discovery and the conquest of America at the beginning of modern times, these peoples systematically performed countless human sacrifices in order to offer the Sun god the pulsing hearts just wrenched out of the tattered chest of sacrificial victims. With this frightening offering they actually celebrated a ritual held to be indispensable for the preservation of life in general, that is of the most precious common good. According to their belief system, life was a gift and a fruit of the movements of the Sun and of individuals; therefore, it only existed thanks to their belonging to the empire of the Sun. To sanction this radical belonging, every midwife, once she had snatched the newborn from their mother’s womb shouted into their ears that their primary duty was “to quench the thirst and the hunger of the sun,” in order to keep it fit along its strenuous journey through the heavens.

The peoples of Mesoamerica believed that the Sun could recuperate the strength necessary to continue to heat and to vivify the Earth only by regaining possession of the magic strength which was liberated from the living and pulsing heart. As a consequence, as the anthropologist J.G. Frazer has written: “Thus the Mexican sacrifices to the sun were magical rather than religious, being designed, not so much to please and propitiate him, as physically to renew his energies of heat, light, and motion. The constant demand for human victims to feed the solar fire was met by waging war every year on the neighbouring tribes and bringing back troops of captives to be sacrificed on the altar. Thus the ceaseless wars of the Mexicans and their cruel system of human sacrifices, the most monstrous on record, sprang in great measure from a mistaken theory of the solar system. No more striking illustration could be given of the disastrous consequences that may flow in practice from a purely speculative error.” (The Golden Bough, A Study in Magic and Religion [New York: MacMillan, 1922]).

All this hecatomb of snatched pulsing hearts did not succeed in either restoring the Sun’s strength, nor even in enhancing anatomy’s body of knowledge. A little vase-statue (recently discovered in Mexico and dating back to the first half of the first millennium B.C.), featuring an individual whose whole body consists of a heart, represents, as far as we know, the best anatomical description of the cardiac muscle produced by that civilisation. It amounts to really little compared with the high price paid in human lives to get to that sketchily “realistic” depiction of the heart.

III. The Heart in Holy Scriptures   

Despite a persistent anatomic confusion between the heart and the stomach (ro-ib), Egyptian physician priests used two hieroglyphics and two words for the heart: they used haty to refer to the cardiac muscle and the word ib to point to the heart both in its spiritual connotation as seat of the soul, of the conscious (ab), of thinking and of desires, and in its physiological connotation of “that which does not stop.” The Hebrew words leb and lebab, used by Israelites to refer to the heart, show clear linguistic resemblance with Egyptian terminology. Recurring Biblical expressions such as “I said in my  heart” (Eccl 1:16; 2:15; 3:17), “it is the Lord who weighs hearts” (Prv 21:2), directly echo Egyptian cardiological beliefs. Just as Egyptian priests did, so Israelites held that in the heart “are the sources of life” (Prv 4,23); that it rested and “refreshed itself” with food and that it is the seat of thinking and the conscious (leb). Yet, despite all these undeniable similarities and derivations, in Holy Scriptures the notion of heart undergoes a semantic shift which, for its approach, depth and wealth of meanings, turns out to be so bountiful and revolutionary to escape the confinements of a  rigid defining formula.

The logical axes which frame this semantic shift can be defined along four structural characteristics. The first is the insistence on the anthropological dimension: nearly all Biblical occurrences of the term “heart” refer to the human heart or to Jesus’ own heart in the NT. Furthermore, such references do not so much have to do with the heart’s anatomic-physiological aspects, as with its anthropological, ethical and soteriological sides. Only in rare instances do we come across metaphorical phrases, such as “the heart of the heavens” (Dt 4:11), “the midst [the heart] of the sea” (Ex 15:8; Jon 2:4), “heart of the earth” (Mt 12:40), used to refer to the centre or the most internal and deepest parts. The second structural element is the radically demythologizing approach that marks Jewish monotheism, firmly opposing any idolatrous divinization of natural forces and any sensible depictions of God. This demythologizing approach, with its pre-Enlightment flavor, drastically drives the heart’s notion away from all the shadow of spirits, cosmic-solar energies and the embellishments of magic-theurgic rituals that had traditionally been condensed in the heart and developed according to the wide-ranging toolkit of ancient heliolatry. The third feature is the unfathomability of the human heart in the Bible: no-one can get to touch the bottom of their heart (cf. Jer 17:9), let alone of that of others. Only God can scrutinize, “weigh” and reveal what lies hidden in the heart of man (cf. Ger 17:10; 1Cor 4:5; Rom 8:27; 1Thes 2:4). This unfathomable depth, causing everyone’s heart to be impenetrable to others and not allowing human beings to ever gain a thorough knowledge of themselves, to ever touch the bottom of their hearts, makes every human investigation of the heart always incomplete, problematic and open-ended.

Finally, – along the fourth structural axis, in some ways the most important one – the Bible generally sees the heart as the chosen setting for an encounter with God, the place where humans’ relationship with God is critically at stake, the seat of its most intimate and profound options. The heart is the logical space where God makes himself known to man, and through which man is confronted divine revelation and action. The conversion to God takes place in the heart, and it is equally there that man listens to Him, and where true worship is rendered. The heart is definitely the first to be engaged in a genuinely authentic act of faith. “Hear, O Israel!* The Lord is our God, the Lord alone! Therefore, you shall love the Lord, your God, with your whole heart, and with your whole being, and with your whole strength” (Dt 6:4-5). The first of all the commandments – as Jesus himself repeats in the same words – “is this: ‘Hear, O Israel! The Lord our God is Lord alone! You shall love the Lord your God with all your heart, with all your soul, with all your mind, and with all your strength” (cfr. Mc 12:29-31; Mt 22:37-39; Lc 10:27-28).

As these passages clearly state, the relationship between “faith in the Lord” and “love of God” in Judeo-Christian thought is one of such mutual implication to make them synonymous: faith in the Lord is nothing but the love of God. It is therefore impossible to understand the nature and the meaning of this love without grasping the focal meaning of the Biblical concept of heart, since what God requires of the genuine believer is not just any devotion, but a love with all their heart and truly from the heart.

Obviously, given its semantic density and the high frequency of its recurrence, in the Bible the word “heart” embraces a very wide range of meanings which have already been identified and listed by Biblical exegetes (cf. Baumgärtel and Behm, 1965; Eichrodt, 1939; Coenen et al., 1978). The heart is the seat of joy and pain (cf. Dt 28:4; Ger 4:19), of unrest (cf. Dt 19:6), of uneasiness and bewilderment (cf. Gv 14:1; 14:27), of fear and rapture (cf. Gdt 11:1; 12:6), of God’s worship (cf. 1Sam 12:24; Ger 32:40), of affections (cf. Dt 6:5; Jud 16:15), of desires (cf. Ex 35:21-26; Ger 29:13), of regret and sadness (cf. Dt 15:10; 1Sam 1:8), of courage (cf. 2Sam 7:29; Sal 27:14), of man’s trust (cf. Sal 57:8; 112:7). The heart, in brief, is the center and root of man’s psychic activity, but certainly not of sentimentalist distortions subjecting human beings even against their will and reason. In the Bible, the heart is not meant to be the exclusive and autonomous source of feelings or the organ of emotions distinct from the organ of reasoning, and it is not supposed to be reduced to that. Quite the opposite: according to the Biblical notion, the heart is seen as the seat of understanding (cf. 1Kgs 3:9; 5:9; Prv 6:32; 7:7) and of memory (cf. Is 65:17; Ger 3:16). Rather than being a merely passive container of thoughts and memories, it is also the organ of every human intellectual operation: the power of thought. It is not accidental that, to say “to think” the Bible uses the phrase “say in one’s heart” (Eccl 1:16; 2:15). God, the only truly and genuinely wise person, is defined as “wise in heart” (Jo 9:4). Not only does one think and reason in one’s heart (cf. Mc 2:6; 2:8), but voluntary and responsible decisions are also taken by it.

The use of the single term “heart” to refer to the whole compound of inner life is, in conclusion, one of the best linguistic proofs to restate the fact that the Bible does not present any rigid dualism of intellect and will, of feelings and reason, of knowledge and virtue, of body and soul. Therefore, when the pious person is invited to love God with all their heart, with all their soul, with all their mind and with all their strength, the sequence heart-soul-mind is not to be taken as a sequence of distinct, autonomous, heterogeneous and therefore mutually irreducible powers; rather, it is to be interpreted as an “explicit statement” of the different aspects of a single and object deep individuality, called heart, which ultimately defines, as W. Eichrodt (1979) has pointed out, the entire personality as a whole, its inner life, its character, the conscious volitional spiritual activity of the human self in its wholeness. The Biblical idea of  “loving with all one’s heart” embraces no irrational emotions; there is no insistence on pure sentimentalism, but rather it depicts both an amor Dei intellectualis and an exciting gratitude for the wonders God allows humans’ hearts and minds to listen to and to experience: in brief, its rationale is a heart-reason involved by God in an endless love dialogue.

The proximity of notions such as leb (heart) and nefesh (soul) found in Biblical texts, sometimes also highlighted by their interchangeable use, further heightens the spiritual implications of the Biblical notion of heart. On the other hand, in Old Testament writings there is a sharp difference between the living breath (ruah) that God breathes into every living being and the living breath (nishmat) given to man. Into the human creature God breathes a “nishmat of life” (cf. Gen 2:7). In the OT this term is used only for God and man. Later Christian exegesis, under the influence of Greek anthropology, granted it the meaning of rational and spiritual soul. The “nishmat of life,” on the other hand, is defined in the Book of Proverbs as follows: “A lamp from the Lord is the human life-breath (nishmat); it searches through the inmost being” (20:27). This definition, among other things, seems to point to something very similar to self-awareness present in the heart, a power of introspection, an ability to know and judge oneself.

In the NT the Greek word kardía occurs in as many as 148 passages, always preserving the OT notion as centre of the conscious and volitional spiritual activity of the person as a whole, but stressing its role as a focal point of religious life. Heart and  mind not only remain semantically close terms (cf. 2Cor 3:14f), but sometimes also occur as synonyms (cf. Fil 4:7). Yet the heart, besides being the seat of misbelief, of wicked thoughts and desires (cf. Mc 7:21-23), is also the place of faith and   conversion, which allows the Holy Spirit to breathe into it His love and live within it (cf. Rom 5:5; Gal 4:6; 2Cor 1:22). The two compound words typical of the NT are also a faithful translation of phrases recurring in OT writings: kardioghnôstes (cf. At 1:24; 15:18) restates the Old Testament idea according to which God is the One Who knows and scrutinizes the depths of the heart; sklerokardía, in turn, translates the Hebrew equivalent compound orlat lebab and indicates the hardened heart of those who, selfishly closed in themselves, refuse to love God and their neighbor.

In Christian spirituality particular importance is to be attached to those New Testament passages that refer to Jesus’ heart. In Mt 11:29 Jesus proposes himself as Savior and Master in the following terms: “Learn from me who am meek and humble of heart and you will find rest for your souls.” In this invitation, modelled on those of the Wisdom of God Herself, Jesus proposes himself as the personified Wisdom and as a model for the “poor in spirit,” that is for all those simple minds, needing knowledge and truth and exempted from pride, which will be restored by listening to the Savior. Jesus’ own pierced side, from which immediately flow “blood and water” (Gv 19:34) is the genuine source of the “water of life” (cf. Jn 4:10-11), which establishes the new alliance of man with God. Theologians and mystics, ever since the Middle Ages, would then attribute to Jesus all that John’s Gospel says about the Redeemer’s pierced side. This way the pierced heart-side of the Crucified takes on the meaning of focal point of the mystery of total love, which gives itself through Jesus’ death on the cross, so that everyone may drink the water of life and receive the Spirit that God pours out into their hearts.

IV. The heart from Hippocrates to Harvey

The rise of a scientific mind-frame in Greece determines one of the greatest philosophical revolutions in human history. The new scientifically oriented approach to the study of human physiology in naturalistic terms is ground-breaking in formulating explanations which are not at all neutral as far as anthropological and psychological issues are concerned. The father of anatomy, Alcmeon of Crotone (6th century B.C.), discovers connections between eye and brain and proposes a physiological cephalocentric model placing in the brain, and no longer in the heart, the seat of sensations, intelligence and soul. This mono-centric physiological paradigm led some Hippocratic physicians to turn the brain into the original source of the vascular system. Even though the philosopher Empedocles (5th century B.C.) had proposed a hematocentric argument claiming that the “blood surrounding the heart is thought,” cephalocentrism was widely accepted in the 5th century B.C. and exerted a great influence on the famous school Hippocrates of Cos (ca. 460-377 B.C.). In this school biomedical research completed that crucial transition from the mythical-pre-scientific stage (when diseases, held to originate from the divine, were treated with spells and magical rituals) to the scientific or rational-naturalistic stage (when diseases turn out to be natural phenomena brought about by natural causes which may be treated through techniques suited to restore the natural balance between humors).

The Corpus Hippocraticum includes the Perì kardies, the work offering the first scientific description of the heart’s anatomy. As Hippocrates writes in the first chapter of this well-known treatise, “as far as shape is concerned, the heart is like a pyramid, it is dark red and it is coated with a smooth tunic.” At the basis of the physiology of the Perì kardies lies the fundamental equation of heart with heat, heat and life. The active principle moving the heart is the “inborn fire.” Heart pulses are brought about the expanding force of this inner fire to which the cardiac tissue only makes passive resistance. The lung, regarded as a cold organ by nature, through breathing gives rise to a heart refrigeration process, thereby causing rhythmically alternating heating and cooling phases which regulate the heartbeat mechanism. By drawing a comparison with the ears of the blacksmith’s oven’s bellows, the Perì kardies outlined a thermodynamic cardiological paradigm which almost all ancient cardiology would draw upon. Within this theoretical framework the left hand ventricle features as the fiery place where a celestial flame burns. Obviously, just like any other flame, the fire burning inside the heart also emits rays tasked with refining blood to turn it into a “pure and transparent residue” suitable for nourishing the left hand ventricle, the seat of the inborn fire. The blood conveys the heat coming from the heart and distributes it to every part of the organism – just as vegetable garden watering canals distribute water to sods.

Plato (427-347 B.C.) reduced the heart-centered sketch of the Perì kardies, by outlining a tripartite physiological paradigm, modeled upon the triadic structure of the soul: the base of the pyramid is occupied by the innards-liver plexus, the seat of the vegetative soul; the heart, being the seat of the irascible soul, is reserved the central area; the brain, being the seat of the rational soul, is granted the honor of occupying the tip of the pyramid, that is the head. Despite the precise match between this tripartite outline and the rigid division of society into three classes, the most interesting part of Plato’s cardiology is the restoration of the thick network of analogies between the cyclical recurrence of biological processes and the circular movements of the stars.

“In the case of every living thing, — as Plato writes in the Timaeus — its inner parts that are close to the blood and the veins are its hottest parts – an inner spring of fire inside it, as it were.” (Plato, Timaeus, transl. by Donald J. Zeyl, [Indianapolis - Cambridge: Hackett, 2000], p. 74). Blood is formed in the stomach-intestine by means of the heat of this inner source by food’s thermic decomposition. Its red color is precisely due to the heat produced by the inner fire it comes into contact with. Once it is produced, blood reaches the heart, the “veins knot” and the watchful sentinel controlling every organ through the vascular apparatus. “The rays of the inner spring of fire” are in any case the real factors which, by following the rhythm of breathing, trigger all other physiological processes, conferring them a cyclical pace. Thanks to this cyclical configuration, the whole of early physiology is structured according to a “cyclical biology,” where each phenomenon is interpreted as an imitation of the circular movement of the stars.

Aristotle (384-322 B.C.), the greatest biologist of the ancient world, explicitly clarifies the dynamic reasons why living cyclical processes imitate the movement of the stars and sketches a single-centered physiological outline which refers to the heart all those functions that cephalocentrism assigned to the brain. Thanks to this reduction, Aristotelian cardiocentrism turns out to be the Greek cardiological understanding which most closely resembles the Biblical one, above all for its psychological and anthropological aspects. Everything originates from the heart. Sperm also comes from it, since it is not only a “residue of blood nourishment” and vessel of the soul, but it is also made up of water and of a spirit which in its nature is “similar to the element the stars are composed of,” that is to say similar to ether, the astral matter that has the property of running all the time. Thanks to this starry “pneuma” coming from the heart and transported by sperm, in the embryogenetic process the first organ to be shaped is precisely the heart, which therefore turns out to be that primum movens of the entire organism designed, just like the stars ether it is composed of, to always move for the whole duration of its life. Right from the third day of incubation “the heart is visible” in a chicken’s embryo “as a red stain in the white part of the egg. This stain pulses and moves as if it were endowed with life.”

The heart, for Aristotle, is the seat of thinking and the origin of veins and of all living functions; it is, in sum, the god of the organism, in the sense that it resembles the god of the universe in being the “first motion” of the organism. From Aristotelian cardiocentrism derives a sort of cardiolatry, centered on the “vivifying spark of nature” burning in the heart and developed according to the heliolatry of early cosmic medicine. It was even too obvious that the ability shown by the heart to keep in constant motion was the central concern of Aristotelian physiology. For ancient cyclical biology nothing was more important than understanding the regulation and preservation mechanism which ensured the long-lasting repetition of the cardiac pulse and, more generally, of the other cyclical living processes. Discovering such mechanisms ultimately meant discovering the secret of life’s preservation. At the dynamic level, on the other hand, the explanation of the unceasing beating of the heart appeared to be a crucial issue, because Aristotelian physics held that all terrestrial motions were provisional, transitory, finite processes, and therefore in themselves unable to guarantee the continuous repetitiveness of periodical motions.

To start with, Aristotle was convinced that there was a sharp dichotomy between the celestial and the terrestrial or sublunar regions: the heavens were the realm of never-stopping motion, because stars were made of ether, that is of a substance that does not consume in motion; the earth was the realm of ever stopping motion, because every terrestrial substance consumes in its motion. The substances that always kept in motion without ever consuming or wearing necessarily experienced perfectly uniform circular motion. The course of the stars was irrefutable evidence of the existence of a mutual implication of a substance’s non dissipative motion and its circular motion: any substance that does not wear in its continuous motion cannot but experience circular motion. Terrestrial substances, due to wear in the course of their processes, could not obviously give rise to thoroughly circular motion, but only to discontinuing periodical kinds of motion which were their only chance of imitating the heavens’ own circular motion. Moreover, the very preservation of terrestrial cyclical processes in a condition of unending repetition could only be guaranteed by eternally circular motion. To sum up, Aristotle argues that continuous repetition of terrestrial cyclical processes resulted from the causal preservation-regeneration activity brought about by the circular motion of the stars and of the sun in particular; it ultimately arose from an overarching celestial macro-determinism or from a “circle-cycle dynamics,” where the eternally circular motion of the stars, fatal wheels of an implacable schedule, governed the pace of terrestrial cyclical events, whose continuous repetition was ensured by the continuous rotation of the fixed stars.

It was much too obvious that the irresistible weight of this dynamics would also be felt in the explanation of the continuous alternation of blood flows and of the continuous pulsing activity of the heart. The search for the underlying causes of the heart’s unceasing beating inevitably ended up connecting the preservation of the cardiac motion with the causes of the preservation of celestial circular motion. Behind the traditional correlation between the blood’s movement in the body and the stars’ circular motion, behind the undisputed belief that all cyclical terrestrial processes imitated the circular motion of the celestial spheres, the pivot of the whole ancient biomedical tradition was the circle-cycle paradigm, which explained the recurring sequence of any cyclical terrestrial process on the basis of the maintaining causality exerted by the heavens. It should not therefore sound odd that for almost two millennia the heart rhythm was seen as an imitation of the solar circle and that nearly circular motion principles were seen occurring in the left hand ventricle, as the eternal circles of the immortal soul, or of an ethereal substance resembling the incorruptible heavenly matter. The inborn ethereal pneuma, the inborn fire or the circles of the souls sequentially located in the heart, were nothing but the principles warranted by the need to put a name on the celestial cause that kept the heart always moving. That there was a dynamic principle of heavenly origin underlying the beating of the heart was a certainty which was then also confirmed by the more solid dynamic and cosmological theories.

The progress of early cardiology did not affect the predominant role of this circle-cycle paradigm, which continued to be the theoretical background of physiology for over two millennia. Herophilos of Chalcedon and Erasistratus of Iulis, the two greatest physicians of the School of Alexandria, who systematically resorted to anatomic dissection and perhaps to vivisection of convicts condemned to death, were thus able to carefully describe heart’s valves and cavities, and worked out a refined diagnostic system centered on pulse analyses. As an alternative to the Aristotelian model, they also put forward a pneumatic physiological model, where the heart mechanism was assimilated to a pump, but it did not enjoy a wide success due to the huge synthesis by Claudius Galen of Pergamum (129-200 ca.), a true giant of early medical studies. Taking up the originally Platonic triadic physiological model, Galen reworked Hippocrates’ physiology in the light of Aristotelian finalism, of anatomic research at the School of Alexandria as well as Stoic cosmology. “At birth —  as Galen writes — an animal is endowed with three principles: one is located in the head, and its internal activities are imagination, memory, thinking and reasoning […]. The second lies in the heart, and its internal activity in itself consists in strengthening the soul, granting the determination needed to do what reason orders and consistency– a feature which seems to match the boiling inborn heat – when reason wants to punish anyone who has committed injustice. As far as the rest of the body is concerned, then, (the heart) is the principle of heat and pulses, respectively, both of the limbs and of arteries.”

Galen supposed that the blood produced by the liver – the seat of the vegetative soul, of the living breath and the origin of veins – was conveyed by veins and absorbed by organs, in same way as the watered ground absorbed water. Along this route a small amount of blood moved from the atrium to the right ventricle and hence part of it was sent to the lungs to nourish them and another very small amount moved from the right to the left ventricle through thin which had to be located in the interventricular septum. With the intuition of a genius he compared the living organism to a lamp: the wick was the heart and blood was the oil burning thanks to the rich pneumatic air absorbed through breathing.

Neither monastic nor Islamic medicine or the refined anatomical descriptions and observations of the heart by Andreas Vesalius (1514-1564) and by Leonardo da Vinci (1452-1519), ever moved away from the basic idea that searching for the causes of the unceasing heart motion was cardiology’s fundamental issue. This idea, which was far from being consequence free, acted as a real epistemological hurdle, which for centuries prevented the rise of any notions of cardiomyopathy. In fact, ancient, Mediaeval and Renaissance traditions would always be very skeptical of looking for the causes of natural death in a strictly cardiological context. Behind the venerable ancient notion of the heart as the beginning and end of living functions, as primum vivens and ultimum moriens, lay in fact the imposing cardiolatric dogma that natural heart arrest would always be a consequence of the other living functions stopping and not vice-versa. The heart, in sum, precisely due to its almost heavenly unceasing motion, could not but be seen as an organ prone to malfunctioning and diseases. All this proved that the fundamental concern of all early cardiology was not to explain heart arrest, but only to explain its long-lasting liveliness.

V. The Heart in Modern Experimental Medicine

Despite the incongruities of traditional cardiovascular physiology highlighted by the discoveries made by Vesalius, Michael Servetus, Andrea Cesalpino, Realdo Colombo and Girolamo Fabrici d'Acquapendente, up until the 17th century cardiovascular mechanics was seen as a continuous production-consumption (tissue absorption) alternation of two types of blood distributed by two vessel systems (veins and arteries) which did not communicate with, and were totally independent from each other. The fact that the blood produced by hematopoietic organs was each time totally consumed entailed the inevitable reduction of the blood flow to a production-absorption cyclical alternation, which in itself could not become truly circular. In 1628, when William Harvey (1578-1657), the father of experimental medicine, showed through simple experiments and certain calculations that within an hour the heart expels an amount of blood exceeding a man’s own weight, he unmistakeably proved that the blood is a substance that holds when it flows through the body and which therefore cannot be produced or consumed all at once by any organs. However, a substance that holds without consuming in its ongoing flow –as Aristotle had already codified – cannot but have a circular motion. Thanks to Harvey’s loyalty to the ancient Aristotelian principle for which every substance that does not consume in its ongoing motion must follow a circular motion, it will be precisely Harvey’s discovery of the blood’s preservation in its flow that will point to the idea of the circulation of the blood, not vice-versa. Actually, Harvey’s discovery can first of all be defined as the discovery of blood’s preservation and, only in a derivative sense, as the discovery of blood flow.

Once blood flowmotion was conceived as circular and therefore as self-preserving motion, the whole cardiovascular apparatus ended up looking like a self-preserving dynamic system. The heart’s very fibrous structure, according to Harvey, showed that its main function resided in contracting, during the systole phase and therefore in expelling blood out of the heart, and not in the diastolic phase, as was thought in Antiquity, when the primary function of the heart was thought to be sucking in blood into the heart cavities. From Harvey’s point of view, not only did the heart look like being the real engine of circulation, but also like possessing an internal self-preserving dynamism. However, once the heart got to be regarded to have an intrinsic ability to keep in constant motion, cardiac physiology escaped the traditional references to celestial circles and the overused sun-heart analogies. Since then, its main problem would no longer be explaining the heart’s continuous motion, but rather looking for the causes of its arrest. With this revolutionary transformation of cardiological discussion, centered more on cardiomyopathy than on early cardiolatry, ancient cosmomedicine gave way to modern life physics.

Descartes (1596-1650), in polemical opposition to Harvey, would look to provide an entirely mechanical explanation of the blood and heart motion, now regarded as the main bellows of the body. Experimental medicine and the use of the microscope gradually managed to break the whole heart enigma. With advances such as those triggered by Marcello Malpighi, who discovered capillary anastomosis, Sénac, who authored the first cardiovascular pathology textbook, as well as following the discovery of oxygen by Lavoisier and of cardiac catheterism initiated by Claude Bernard and perfected by Werner Forssman, the development of cardiological knowledge experienced an exponential acceleration. This is not the place to outline the fascinating history of this development, which has already been widely analyzed by historiographers; on the other hand, it is worth remarking how the understanding of the cardiovascular system was greatly accelerated by the extraordinary development of cardiological instruments. Ranging from the device to measure arterial pressure to Laennec’s stethoscope, from electrocardiography – following the discovery of the bioelectricity of neuromuscular tissues, thanks to Galvani and Matteucci, and the discovery of the difference in electric potential between an area of excited tissue and a dormant area – to the mathematical modeling of the heartbeat by Balthasar Van der Pol, from pacemakers to CAT, NMR and eco-cardiography, the technological evolution of diagnostic implements has disclosed all the secrets of the heart. The recent history of heart surgery witnessing even more visible successes, ranging from the aortocoronary by-passes, to the introduction of valve prostheses, from the heart-lung machine for extra-body circulation up to the implant of an artificial heart, would seem to have solved all the enigmas of the heart replacing them with the functional clarity of a machine with no secrets.

If they are judged only with the eyes of scientific analysis, the mysteries of life, thought and conscience no longer lie hidden in the inscrutable depths of the heart, but seem to have moved to the frontiers of the genetic code and the mind-body relationship. The recent developments of cardiology have completely upturned Harvey’s idea that only God was able to know the physiology of the heart. With his upturn, all the complex web of anthropological, psychological, spiritual and mystical conceptions, which was built in ancient times around the human heart no longer holds to its original bond with the noblest and shiniest of all human organs. It is not surprising, therefore, that the very semantic networks built around the heart in the past have been subjected to such shifts in their meanings to completely modify the original sense of those notions interconnections. A clear example of this is the change in meaning which the expression “I believe” underwent in the Modern Era. According to its Latin etymology credo means “cor do”, that is “I offer or give my heart.” Hence the statement “I believe in God” originally meant: “I offer my heart, my life, my soul, my worship to God, the Being that exists by Himself.” Nowadays, by contrast, in ordinary language, it seems to refer to the meaning of accepting an uncertain opinion, perhaps only a hope. In this respect, remembering its original meaning can offer multiple incentives for reflection.

Read also: 

F. BAUMGÄRTEL, J. BEHM, Kardía, in TDNT, vol. 3, 1965, coll. 605-614; E. CLARKE, C. O’MALLEY, The Human Brain and Spinal Cord (Berkeley: University of California Press, 1968); L. COENEN, E. BEYRENTHER, H. BIETENHARD (eds.), The New International Dictionary of New Testament Theology, English edition by Colin Brown (Exeter: The Paternoster Press, 1978); L. CONTI, M. BALDINI, M. TIMIO, Il cuore dal circolo cosmico al trapianto (Milano: Ciba Edizioni, 1997); W. EICHRODT, Theologie des Alten Testaments, 3 vols. (Leipzig: J.C. Hinrichs, 1935-1939); PH. GORNY, Histoire illustrée de la cardiologie de la préhistoire à nos jours (Paris: Les Editions Roger Dacosta, 1985); C.R. HARRIS, The Heart and the Vascular System in Ancient Greek Medicine from Alcmaeon to Galen (Oxford: Clarendon Press, 1973); N. LATRONICO, Il cuore nella storia della medicina (Milano: A. Recordati, 1955); P. MANULI, M. VEGETTI, Cuore, sangue e cervello. Biologia e antropologia nel pensiero antico (Milano: Episteme Editrice, 1977); M. MATTIOLI, La scoperta della circolazione del sangue (Napoli: Edizioni Scientifiche Italiane, 1972); M. MESLIN, Heart, in The Encyclopedia of Religion, M. Eliade, ed. in chief, (New York: Macmillan Co., 1987), vol. 6, pp. 234-237; W. PAGEL, New Light on William Harvey (New York - Basel: S. Karger, 1976); E. SCHRÖDINGER, Science and Humanism (Cambridge: University Press, 1951); E. SCHRÖDINGER, What is Life? (Cambridge: University Press, 1948).

Paolo Zanna