“Some say that we owe our consciousness to our hearts and that it is the heart which suffers pain and feels anxiety. But this is not the case; rather, it is torn just like the diaphragm, and even more than that for the same reasons: for blood-vessels from all parts of the body run to the heart, and the heart encapsulates these, so that it feels any pain or tension occurring in a human being. Moreover, the body inevitably shudders and contracts when it feels pain, and likewise when it is overwhelmed by joy. This is why the heart and the diaphragm are particularly sensitive. Yet neither of these parts has any share in consciousness; rather, it is the brain which is responsible for all these.”

These words derive from the author of the Hippocratic work On the Sacred Disease, a medical text about epilepsy written in Ancient Greece c. 425 BCE. It reflects a very early stage in a debate that was to have a long history – a debate between physicians, philosophers, scientists, psychotherapists, but also poets and other intellectuals about the location of the mind and the physical basis of personality and the emotions. Throughout the history of medicine, various bodily parts were suggested as candidates, and all sorts of arguments and evidence were presented in favour of a particular thesis. But the debate was never fully settled until the late 19th century.

And some aspects of the issue are still with us today, in the way we think and speak of our emotions in relation to our bodies. For it touches on the relationship between the mental and the physical, and how the one impinges on the other – a relationship that continues to be only partially understood. For example, we all accept that there is a correlation between stress and heart disease. But how exactly does this work? Is stress psychological or physiological? How do emotions, feelings and beliefs ‘translate’ in physiological terms? And vice versa, how do physical conditions like blood pressure impinge on our mental and emotional wellbeing?

Aristotle’s camp

Typically, the Greeks were the first to raise questions of this kind. And although their knowledge of anatomy and physiology was, of course, very limited by our standards, their awareness of the issues and the sophistication of their discussions is striking.

Thus the 4th-century BCE philosopher Aristotle advances a psycho-physical theory of emotions like anger, which he defines both as a “seething heat in the region of the heart” and as “a desire for retaliation”: these two definitions are complementary descriptions of one and the same emotional state, the former referring to the physical, the latter to the psychological.

According to Aristotle, each emotion or mental process should be described along these psycho-physical lines, just as, on a more general level, ‘mind’ and ‘body’ are two inseparable aspects of one and the same thing, a human being. Aristotle carefully steers a middle course here between idealism, which radically denies that mental states have any physical aspect, and reductionism, which reduces all emotions to physical processes.

In Aristotle’s view, the heart is the central part of the body, both spatially and in terms of hierarchy. It is the part that is formed first in embryological development. It is the source of bodily heat and thus primarily responsible for nutritive functions. And it is the primary seat of emotions and sensations, for it houses the ‘central sense organ’, a kind of coordinating centre that processes the information derived from the peripheral sense organs (with which it is connected through the blood vessels) and that issues decisions to the limbs and other parts of the body involved in action and motion.

Thus Aristotle takes a radically different view from the Hippocratic writer quoted above. In Aristotle’s theory, the brain has no psychological significance, it is just there as a kind of refrigerator, balancing the bodily heat generated by the heart and exercising a cooling influence on the process of digestion.

But Aristotle was neither the first nor the last to advance the cardiocentric view. In Classical Greece and Rome, it was generally believed that the heart played a major role in the mediation between the mental and the physical. And initially it was the heart, rather than the brain, that was considered to be the seat of mental processes, including intellectual functions like thinking, memory and imagination.

From Homeric times onwards, humankind’s thoughts, beliefs, but also emotions and states of mind like anger, ambition, courage, valour, grief and pride were located in the upper parts of the thorax, in the diaphragm or the heart. And although the physiology of the heart and the pulse were only partly understood, there was little question about the central importance of the heart in the functioning of the human organism as a whole. The cardiocentric theory of the mind became the dominant view in antiquity and was upheld by medical writers but also by the Stoics, a school of philosophers with strong medical interests, who regarded it as the seat of the ‘ruling part of the soul’ – the intellect.

Plato’s response

However, it was characteristic for the argumentative nature of Greek medicine that there was widespread disagreement about this issue, and rival views continued to have their advocates. Several medical writers and philosophers, such as Empedocles, attributed a major role to the blood as the intelligent and life-giving substance in the body. And there was also the encephalocentric theory, defended not only by the Hippocratic author quoted above but also by the philosopher Plato. Plato distinguished three ‘parts’ of the soul – mind, spirit and desire – which he located in the brain, the chest and the belly respectively.

Yet while Plato and the Hippocratic writers based their views largely on speculation and on occasional findings derived from animal anatomy, a more ‘scientific’ view emerged when Greek physicians in 3rd-century BCE Alexandria dissected the human body and discovered the nervous system. Their views were more fully developed by the Roman authority Galen in the 2nd century CE, who in a series of experiments on animals showed that it was the brain that was the origin of the nerves and the centre of sensation, consciousness, speech and intelligence, thus depriving the heart of any cognitive significance.

Yet Galen’s experiments were not sufficient to persuade the Aristotelians and Stoics, who continued to stress the central role of the heart. For emotions, they argued, also have a cognitive aspect to them, just as beliefs and thoughts are often accompanied by feelings of pleasure and pain.

In order to account for this, Greek medicine characteristically resorted to two speculative ideas: the concept of pneuma or ‘spirit’, a kind of delicate airy substance within the body that was believed to mediate between the brain and the heart, between thoughts and emotions, and to be responsible for the translation of ‘mental’ states into ‘physical’ action and vice versa; and ‘sympathy’ (sympatheia), a notion that was called in to account for the simultaneous emotional experiences in different bodily parts, and which proved to be a very useful concept to refer to psychosomatic connections that escaped empirical validation.

Today, modern medicine has little time for concepts such as ‘spirit’ or ‘sympathy’. Yet the Ancient Greek view of the heart and viscera’s role in our emotional states remains deeply embedded in popular culture. We still, apparently, make decisions with our heart as well as our head.

See also

• Limiting damage from lack of oxygen
• Scientists in cardiovascular harmony
• Genes that control the asymmetry of the heart
• The virtual heart
• Cardiovascular disease in Eastern Europe
• Cardiovascular stress and sleep apnoea

External links

• On the Sacred Disease by Hippocrates