Historical Introduction
Cardiocentrists versus Cerebrocentrists
The Platonic Heart
The Aristotelian Heart
The Hippocratic Heart
Conclusions
Images of the heart past and present
Related web-sites and some cool, but not quite related web-sites
Bibliography
Look at the comments on this paper.
It is only the size of a fist, and yet it is central to human existence. It has been the subject of poetical discourse and scientific scrutiny, anatomical debate and lovers quarrels. It is the human heart.
This paper shall examine ancient views on the human heart through descriptions given by Plato in the Timaeus, Aristotle in some of his biological texts, and the "Hippocratic" text On the Heart. The descriptions for Plato and for the Hippocratic treatise will be examined directly and supplemented by commentary. Aristotle's description will be taken from secondary sources.
Human anatomy has fascinated many since early antiquity. It is somehow ironic, though, that for all of man's curiosity about his own structure, until rather recently it was taboo to really investigate it. For a great part of human history, human dissection has been forbidden and abhorred, generally for religious reasons [French, R.K., 1 (1978), p. 10]. Without human dissection, no real knowledge of the internal structures of the human body can be ascertained. The ancients had four indirect means by which they could learn about man's internal structures:
2) inferences from the externally visible structures of man
3) from natural philosophy as a whole
4) from function [from French, R.K., 1 (1978), p. 10]
This list may seem completely inadequate for any real scientific investigation, but it is possible to infer much using these four categories. First, through the butchery, disemboweling, and preparation of animals to be eaten, most of the major organs and two major blood vessels were known. There was also a rough idea of their relationships to each other in the body [French, R.K., 1 (1978), p. 10]. Two major blood vessels are visible on the necks of people; it seemed logical to conclude that those two vessels continued through the thorax and the abdomen. The heart seemed to be connected to the vessels in some way, but until anatomical dissection became established as a discipline, there was no way to know for sure [French, R.K., 1 (1978), p. 10]. Natural philosophy contributed the idea that the basic principle of life had some specific location in the body. This basic principle was "hot, mobile, associated with breath, and, it was widely thought, it preserved some kind of life of the individual" after the death of the physical body [French, R.K., 1 (1978), p. 10]. This basic principle is really the idea of the soul. Early natural philosophers had great debates over which organ was the seat of this soul. Lastly, by function, it could be ascertained that there are some things that separate the living from the dead. A living person is warm, breathes, moves with an innate motion, and moves in reaction to external changes. The dead have none of these qualities [French, R.K., 1 (1978), p. 10]. The living have use of the senses, but the dead do not. Also a dead body becomes stiff and will not bleed the way a living body will if pricked or cut. It was also known that man could not live long without breathing, nor with out food or drink for an extended period of time [Harris, C.R.S. (1973), p. 35]. These were the basic ideas that men knew about anatomy until the bright light of Alexandria.
In the third century B.C. in Alexander the Great's city of Alexandria, there was the first anatomical revolution. For the first time, the systematic dissection of human beings was allowed and widely practiced [French, R.K., 2 (1978), p. 153]. The vivisection of people (generally criminals of the court) was also allowed; vivisection is the dissection of people when they are still alive [French, R.K., 2 (1978), p. 154]. Alexandria was a mix of Egyptian and Hellenistic cultures, and the arts and sciences were fully patronized by the Ptolemies (the ruling family over Egypt after the death of Alexander). Many cultural ideas and beliefs were tolerated, and no single philosophy was allowed to dominate [French, R.K., 2 (1978), p. 153]. But why was human dissection allowed? First, the opening of the body was essential to the Egyptian practice of embalming, and this was well known to the Greeks. Next Plato and Aristotle had emphasized the separation of the body and the soul; the body was simply a house for the immaterial soul. The soul was what really mattered; the body became nothing more than an empty shell after death. Hence, any subsequent mutilation of the body mattered very little after death [French, R.K., 2 (1978), p. 153]. Also, Aristotle emphasized the great importance of the senses in the investigations of science [French, R.K., 2 (1978), p. 155]. Two other factors that were important to the practice of anatomy as a discipline were the establishment of a medical school, providing a sanctioned place and a reason for dissections. Anatomy was and is today an important part of the medical school education as a teaching device. Also, anatomical and other medical texts were being produced. The need for anatomical and other medical texts grew with the breakdown in the oral transmission of medical information. It became necessary to write things down [French, R.K., 2 (1978), p. 153]. So the practice of human dissection flourished in Alexandria, and great discoveries were made in the anatomy of the human heart as well as other internal structures.
Cardiocentrists versus Cerebrocentrists
Through the centuries of speculation and guesswork, the heart became involved in an area of some controversy. The ancients were concerned with which organ was the seat of the soul and acted as the seat of reason. Some believed that the heart served this function; others thought that the brain did. Those in the heart faction are cardiocentrists; those in the brain faction are cerebrocentrists.
The Egyptians were cardiocentrists. They treated the heart with reverence during their embalming rituals; the brain was considered worthless and removed through the nose. Ancient Indian medicine also gave special reverence to the heart [French, R.K., 1 (1978), p. 11]. The ancient Greeks of Homer's era brought in the idea of two souls in the body: the psyche that ensured personal immortality and the thymos that dealt with the more material aspects of life such as motion, life-energy, and heat. The thymos was the breath-soul and part of a larger "common life of the universe." The thymos was believed to be breathed in at birth and breathed out with the last breath before death. In Homer, the psyche rested in the head while the thymos rested in the chest [French, R.K., 1 (1978), p. 11]. The experiences of ancient Greeks and Egyptians with the effects of head traumas drew attention to the cerebrocentrist idea. A person could be knocked unconscious (psyche would be affected) while the body still lived (thymos would keep corporeal functions going). [French, R.K., 1 (1978), p. 11].
The Pre-Socratics debated the issue as well. Alcmaeon, who is said to have dissected eyes and observed the connection of the optic nerve to the brain, was a cerebrocentrist [French, R.K., 1 (1978), p. 12]. The medical school of Croton is said to be cerebrocentrist as well. The medical school in Sicily (the Sicilian school) believed the heart to be the most important organ in the body. Philolaus (fifth c. B.C.) believed that the nous (mind) was in the brain, but the psyche (soul) was in the heart. He also believed that the umbilicus was the source of growth in the body, and hence the third most important organ [French, R.K., 1 (1978), p. 12]. Empedocles was a cardiocentrist [Phillips, E.D. (1973), p. 23].
The Hippocratic treatise The Sacred Disease is cerebrocentrist. Diogenes of Apollonia was also cerebrocentrist [French, R.K., 1 (1978), p. 13]. Other Hippocratic works vary in their allegiance to the cardiocentrists or the cerebrocentrists [Phillips, E.D. (1973), p. 43. The Cnidian school was cardiocentrist [Harris, C.R.S. (1973), p. 34]. Plato, who will be discussed below, believed in a tripartite soul, with the rational soul being located in the head, closest to the heavens [French, R.K., 1 (1978), p. 13]. The other two parts of the soul, the mortal nobler soul and the mortal baser soul, are located lower in the body, in the chest and midriff, respectively. Aristotle was a cardiocentrist. Diocles, a supposed follower of Aristotle, was a cardiocentrist [French, R.K., 2 (1978), p. 154]. With the rise of Alexandria and the establishment of human dissection, the central nervous system was discovered; finally it was known that the brain, spinal cord, and nerves were "the organizing center of the body" [French, R.K., 2 (1978), p. 155]. Aristotle's influence on the debate, though deeply rooted and strong, was increasingly more difficult to defend as more discoveries were made about the nervous system [French, R.K., 2 (1978), p. 155]. This eventually lead to the end of the argument, with the cerebrocentrists victorious.
It is important now to go backwards to the times of Plato, Aristotle, and "Hippocrates" (d. 357 B.C.) in order to examine and discuss each of their views on the structure and function of the heart.
Plato's description of the heart comes as part of a larger description of anatomy and Hippocratic medical and humoral theory from the Timaeus (c. 367 B.C.). The translation summarized below comes from Cornford, F.M., trans. of Plato. Timaeus. New York: Macmillan Publishing Company, 1959, passages 69b-71b.
According to Plato, people were created by the divine creator who formed people following a certain set of ideas. First the immortal and divine soul was created. Then a body was fashioned to house it. Next another sort of soul was created; this was the mortal soul. It contained pleasure, temerity, fear, passion, hope, irrational sense, and desire; these are the bases of many human weaknesses, but nevertheless Plato points out that these are necessary to pair with the immortal soul, if man is to survive. The mortal and the immortal soul were housed in separate places in the body, in order to prevent the mortal soul from polluting the immortal soul. The immortal soul was placed in the head, and the mortal soul, found to have a nobler part and a baser part, was divided into two parts and separated, again to prevent one from polluting the other. The nobler part rests in the breast, and the baser part rests in the trunk. A partition was placed between them.
The part of the soul that is more "manly spirit" was put closer to the head so that it could be closer to and listen to reason; then they could join forces to restrain the desires, whenever they might wish to misbehave. The heart is described as "the knot of veins and the fountain of the blood." The lungs are soft and bloodless and rather like a sponge; they act as a cooling and a cushioning agent for when the spirit boils with anger at some act of wrong taking place, or when the heart throbs "when danger is foreseen." The lungs buffer the heart and cool it down so that the spirit may be better able to listen to and follow reason.
The third part of the soul, the part concerned with food and drink and other bodily needs is housed between "the midriff and the boundary toward the navel." It is farthest from the part of counsel so that it might cause the least trouble since it cannot understand reason, and even if it could, it would not heed it.
Plato is much more concerned with the soul than with the heart. He has very little to say about the heart or its structure. From his description it sounds more like a fusion of blood vessels than a separate organ. Plato's purpose, however, was not to write an anatomical treatise. Rather he is describing the human body as it follows his own philosophical ideals concerning the soul. Plato is really a cerebrocentrist, meaning that he believes that the head is the governing part of the body. In this specific case, the immortal, or reasonable soul is the overall ruler of the body, with two other but inferior mortal souls inhabit other areas of the body. The nobler mortal soul does not even specifically rest in the heart, but rather it seems to rest vaguely somewhere in the chest so that it may affect the heart. It should be noted that Plato does not intend to forward the idea that there are three separate souls, but rather that there are three parts of the entire soul (a tripartite soul) [Taylor, A.E. (1928), p. 498], composed of the "palace inhabited by the rightful monarch", the "guards", and "the business quarter" [Taylor, A.E. (1928), p. 500]. Plato is imposing his own political views on a scheme of the human body [French, R.K., 1 (1978), p. 13].
Aristotle discusses the structure of the heart in a few of his treatises, such as Historia Animalium and De Patribus Animalium.. He was a firm cardiocentrist, and he performed many experiments to gain empirical knowledge and evidence for his theories. Since human dissection was not allowable at the time, he used animals and the other three indirect methods of gaining anatomical knowledge mentioned earlier in the paper to the best of his ability [French, R.K., 1 (1978), p. 14]. Aristotle theorized that since the heart was "central, mobile, and hot, and well supplied with structures which served to communicate between it and the rest of the body;" it was a single and central organ, and so it was most suitable to being the seat of the soul [French, R.K., 1 (1978), p. 15]. It should be noted that Aristotle was not aware of the central nervous system; it would not really be discovered until much experimentation and dissection had been done at Alexandria.
Aristotle's heart had three chambers, and there were two significant vessels connected to it: the vena cava and the aorta; he does not mention the valves [Lonie, I.M. Part I (1973), p. 8]. The right chamber has the hottest blood and the most abundant blood; the left chamber has the coldest blood and the least abundant; finally the middle chamber had the purest and thinnest blood in the body and a medium quantity. The method he used to kill the animals might account for the difference in amounts among the chambers he describes. Aristotle would strangle the animals, resulting in the veins and the right side of the heart being full of dark blood while the left side would be drained [French, R.K., 1 (1978), p. 15]. Aristotle believed the heart to be the starting point of the veins.
The aorta and the air-filled arteries connect to the middle chamber. The vena cava, the "great vessel," is connected to the largest cavity. All three cavities have channels to the lungs, but two of those channels are too small to be clearly seen. It is not clear how the air returns to the heart, whether it is by the same vessel or a different one [French, R.K., 1 (1978), p. 16]. The heart is the source of heat; the left side of the heart deals more with air than with blood, and the contents are purer [French, R.K., 1 (1978), p. 16]. He does not seem to recognize the valves of the heart, but he does recognize the difference between arteries and veins [French, R.K., 1 (1978), p. 16]. He describes the vena cava and the aorta in great detail, along with various superficial veins such as the jugular [French, R.K., 1 (1978), p. 17]. In Aristotle's description the two halves of the heart work as separate systems each having its own set of blood [French, R.K., 1 (1978), p. 17].
Aristotle criticized Plato for describing the heart as a cushion [Lonie, I.M. Part II (1973), p. 144]. Aristotle also takes a functional view of the heart's anatomy to some extent. He believes that the rather thick wall of the middle chamber is due to the need for guarding the source of heat; this sounds rather like the author of On the Heart mentioned below if we presume that the middle chamber of Aristotle is the same as the left chamber in On the Heart [Lonie, I.M. Part II (1973), p. 145]. Aristotle also believes that the air breathed into the body is not pneuma , but rather it acts as a coolant for the heat of the heart [French, R.K., 1 (1978), p. 14].
The main source for anatomical information about the heart from the Hippocratic Corpus comes from a called On the Heart (or De Corde). It is a clear and concise description of the heart; however, there are some difficulties surrounding it. The date of the treatise is very uncertain. It is generally accepted by scholars that it is a late work, perhaps much later than the rest of the Hippocratic Corpus [see Lonie, I.M. Part I (1973) pp. 2-8. for a full discussion on the question of the date of the treatise; see also Harris, C.R.S. (1973), pp. 83-85]. For the purposes of this paper, the date of the treatise will be approximated in the third century B.C. perhaps at Alexandria, during the height of scientific experimentation and activity there.[Lonie, I.M. Part I (1973) p 10.]. The description of the heart that follows is summarized from I.M. Lonie's translation of On the Heart that appears in G.E.R. Lloyd's (ed.) Hippocratic Writings. London: Penguin Books, 1978, pp. 347-353.
According to the Hippocratic treatise On the Heart (or De Corde), the heart is shaped like a pyramid and is a deep crimson color. It is contained in a membranous sac (known today as the pericardial sac) and surrounded by fluid that helps absorb the heart's heat. This fluid comes into the sac from the lungs. Apparently while a person is drinking, a small amount of the liquid goes into the larynx rather than the gullet. The amount is small enough that it is not felt, and the epiglottis fits securely enough that it only allows this small amount (approximately one drink) into the larynx. This water moistens the larynx and does not interfere with the passage of breath. Once the fluid is in the lungs, the heart draws it in, along with air. Once the heart has used the fluid and the air, both are sent back into the lungs; however, a small amount of the liquid drips into the sac. Hence there is the fluid in the sac.
Then the author moves an anatomical description of the heart itself. The heart is an extremely strong muscle. It is located in the left side of the chest. In the heart, there are two cavities which are dissimilar; they are the right and left cavities, or chambers, (designated by facing the heart as it is stationed in the chest). The right chamber is much more spacious inside than the left chamber. The apex of the heart is solid muscle. The left cavity lies a bit lower than the right cavity and has a thick wall. It is surrounded by the lungs, and the cooling effect of the lungs (they are naturally cool, and respiration cools them as well) helps to temper the heat of the left chamber. Its pulsation can be observed in the left nipple. The surface inside each chamber is rough, the left chamber being rougher than the right. This is because the innate heat of the heart is located in the left chamber rather than the right chamber, and the untempered heat roughens the inside surface. This is also why the walls of the left chamber are so much thicker than the right chamber's walls: it protects against the untempered heat.
If one removes the tops of the "ears" of the heart, the orifices of the chambers are exposed. From these orifices rivers that irrigate the "mortal habitation" flow into the body. If these rivers dry up, then the person dies. The ears are soft, and they enfold the heart. They are the means by which the heart controls respiration. They work the same way as the bellows of a blacksmith work. Air is drawn in and pushed out with the expansion and deflation of the ears. This is necessary since the heart is so dense and therefore lacking in "attractive power". The evidence for this purpose of the ears is the fact that while the heart pulses, the ears have a separate movement as they inflate and collapse.
Veins are the means by which the left cavity inspires (or receives air from the lungs); for the right cavity, an artery is the means. The softer vessels (the veins) have greater attractive power since they are more capable of distention. The left chamber requires more air, and hence more cooling, since it is the seat of the innate heat; the other chamber does not need so much cooling, and thus it needs less air.
Now the author turns to the "hidden membranes" of the heart. There are membranes and fibers spread throughout the chambers, like cobwebs, especially around the orifices. There are filaments implanted into the walls of the chambers as well. The author believes these to be "guy-ropes and stays" of the heart and the vessels as well as a foundation of the arteries. There are two arteries, each of which has three membranes at the entrance. These membranes are shaped like semicircles, and they fit precisely together so that neither air nor water can be forced through. This can be seen in the heart of a cadaver, if one places the membranes together correctly. The membranes of the left chamber fit especially well. This is not unexpected since man's intelligence (gnome), which rules over the rest of the soul, is located in the left cavity.
The soul is nourished via a "pure and luminous substance" that is refined out of the blood. Here the author may be referring to a mysterious substance known as pneuma, a product of moisture and heat (see Lonie, I.M. Part II (1973), pp. 147-149, for a discussion on pneuma). This substance is transmitted through rays from the neighboring "blood receptacle". While this is happening, the membranes to the great artery (i.e. the aorta) are closed off. The great artery receives its nourishment from the belly and intestines. This food is "not fit for the ruling principle", or soul, and should not mix with the proper food for it. This is the reason for the membranes. The author provides empirical evidence for the theory that regular visible blood is not the nourishment for the left chamber and the intelligence-soul there. If one opens the left chamber of an animal's heart right after death, if it has been killed by slitting its throat, one will find no blood in the left chamber, but rather only some serum and bile. Blood will be found in the artery and the right chamber.
There is a vessel leading from the right chamber to the lungs that provides nourishing blood. This vessel also has a set of membranes that may close off the entrance of the vessel. However, those membranes do not seal as tightly as the ones in the left chamber, and a small amount of air may pass through. The heart is weaker in this part, as it is dominated by a mix of cold. The innate heat is in the left chamber. According to the author, blood is not hot by nature, but rather it may become hot if heated. Here ends the treatise On the Heart .
From this treatise it seems rather clear that the author knew quite a bit about heart anatomy from direct observation of the human heart as well as animal hearts. Despite some ambiguities and corruptions in the text, [Lonie, I.M. Part I (1973), p. 9.] he gives a fairly clear description of the ventricles, the vessels (recognizing the difference between arteries and veins), and the semi-lunar valves. It is not clear whether the author is recognizing two valves or four. It is clear at one point that he is describing the semi-lunar valves in the latter section of his description; however it is not clear whether or not he is describing the atrio-ventricular valves in the previous section. The text seems to be corrupt here, and Lonie gives a more detailed discussion on the debate surrounding its interpretation in Lonie, I.M. Part I (1973), pp. 11-14; see also Harris, C.R.S. (1973), p. 88. The author does recognize the property of the valves that allow for only uni-directional flow [French, R.K., 2 (1978), p. 156]. The treatise recognizes that blood is in both the arteries and the veins. It does not say anything about the pulsation of the arteries.
According to Lonie, I.M. Part II (1973), p. 144, the treatise is striking in its teleology. The author discusses the anatomy and physiology of the heart in view of the function of the organ. Differences in anatomy indicate differences in function. The function of the thicker walls surrounding the left cavity is protection from the strong innate heat located there. The auricles ("ears") have the function of drawing in the air from the lungs. The entire treatise leads up to the description of the semi-lunar valves, described as a "masterpiece of Nature's craftsmanship." The function of the semi-lunar valves is related in part to the proper nutrition of the soul in the left chamber. If the date of the treatise is truly closer to Aristotle than the Hippocratic Corpus, then the idea that Nature used reason in creation was quite popular. This meant in theory that man could eventually understand the construction of the world through divining the reasoning behind it. Anatomy therefore developed the focus away from using the body solely as a learning tool for understanding its structure and function and more towards the body as "a philosophical exercise in learning how the body was constructed" [French, R.K., 2 (1978), p. 155].
The ancient Greeks were very curious about the human body. They did the best they could with the tools at their disposal to investigate and postulate the nature of the human body as well as its functions. This is seen clearly concerning the heart. It has experienced variable consideration, from those who believed it to be the central organ of the body and the seat of the soul to those who saw it as nothing more than a knot of veins. The history of the heart in Antiquity is one that shows how little progress could be made in anatomy before the introduction of organized human dissection as a discipline. For centuries man has been fascinated by the heart. Whether it is the seat of the soul, the seat of passion and emotions, or simply the subject of poet's ramblings, it is vital to human life and to human culture. It is only the size of a fist, but it is powerful; so is the history of its description.
Related Web Sites
The Visible Human Project
Milestones in Cardiac History
The Heart exhibit at the Franklin Library
Pictures at the National Library of Medicine
Heart Valve Lab
Interactive frog dissection
Questions and answers about the heart and blood vessels
Cool, but Unrelated Web Sites
Institute and Museum of History of Science in Florence, Italy
History of Physics - pictures of instruments
Medical texts, annotated bibliographies online from the Medical College of Georgia
`De Proverbio' - an article on medical aphorisms
Seven Wired Wonders of the World
Classics and Mediterranean Archaeology home page
Chronological list of Mathematicians
