A Treatise on Treatises: On the Movement of the Heart and Blood (Part 2)

Ah. You're back? I didn't imagine you had the stomach for my brand of storytelling. Well, I won't bore you with much inane chatter. This is The Heart Part 2 (by Not Kendrick Lamar). Let's jump right in!

 

We closed off the first instalment with a cryptic Reverend Insanity reference and a promise to visit the wider medical traditions of the world. At least with respect to the heart. Join me in the Dragon country. Cue my erhu music. Centuries before Galen began his misadventures, physicians of the Han dynasty had already conceptualised that blood flowed centripetally (returning towards the centre “centre-petere”) in the body. This was not mechanically or quantitatively derived but was an explanation rooted in the philosophy of completeness and circulation that remains a mainstay of the region to this day. “The blood flows continuously in a circle and never stops... It flows like the water in a river or like the sun and moon in their orbits,” - Huangdi Neijing, Su Wen (Chapter 39). Chinese scholars saw the body’s blood circulation as identical to river systems, tides, and seasonal cycles. You don't “measure the math of a river” to keep it from flooding. You manage its channels, clear blockages, and maintain its seasonal balance. Their understanding was consolidated in their system that included the idea of spirit energy as Qi, and the meridians (Jing-Luo) — energy channels of the body. This also formed the basis for what we would understand as acupuncture, cupping therapies and the herbs they used. The Chinese described a theoretical, energetic loop of blood flow (Xue) and Qi, but they did not map the exact physical distinctions between arteries, veins, and cardiac valves, nor measure blood volume mathematically. And I mean, why bother? With just this base, they developed hyper-sophisticated pulse-reading techniques that served to diagnose internal systemic illness via blood flow at various radial artery points. Rather to look at the quality of the pulse and determine what it means and oddly, it worked! Where a modern Western doctor measures a pulse as a simple number (e.g., 72 beats per minute), a Chinese physician by the Tang and Song Dynasties had mapped over 28 distinct pulse categories across 3 positions and 3 depths on both wrists. Impressively, all these categories were empirically tested and held true in their system, it may not have had the fixed measure of numbers but the underlying condition for a disease could still be determined by feeling a person's pulse and if it was a wiry pulse, the person probably had liver disharmony. I wonder what they'd say about me livering myself working on this. While they did not have a humoral system like the West, they also had an elemental governance of their own. Water, Wood, Fire, Earth and Metal. These fit into their cosmological understanding of the world and the philosophies they live by.

Inner Canon of the Yellow Emperor (2698 - 2596 BCE): Text introducing fundamental philosophical themes of the classical Chinese tradition, the symbolic vision of nature and the body, the dynamic relationship between the elements for the harmony of health, the correspondence between the natural ‘Five Movements’ and the theory of Yin and Yang, the pathway to wholeness of body and mind, the analysis of Qi, the main elements of physiology and basic diagnostic and curative models such as phytotherapy and acupuncture.

Onwards! Let's look at the Golden Byzantium and Islamic society. For a time, they were the sole bridge between the East and the West and if living in new age capitalism should teach you anything it's that there's money in moving things. Taxes! Merchant trade! The whole shebang. It saw their state bursting economically, so what did they do? They made the most robust healthcare system of their time. The state funded research and expanded healthcare access in the region. The Bimaristan System had specialised wards, teaching institutions and robust licensing of physicians. It was also an age where Galenic thought was expanded and challenged. Al-Razi was one of the first to challenge the humoral system and pioneered the use of catgut for suturing. We have Al-Zahrawi coming up with 200 surgical tools that would go on to be the regular European surgeon's toolbox in ages to come. There was as well Ibn Sina (Avicenna) a man who truly worked in his capacity as a bridge between Indian medical traditions and the Galenic school, synthesising a unified system of medical discipline. He laid down the early framework for experimental pharmacology and hypothesised the existence of invisible airborne and/or waterborne substances that cause disease conceptualising the idea of contagion. His contributions inspired more still to look beyond what their predecessors handed down to them at face value. More like Ibn al-Nafis who chronologically was the first to challenge Galen's interventricular septum and posit the existence of pulmonary circulation of blood. Unfortunately, his logically deduced ideas would turn out to be far beyond the practical needs of his time and would be doubly doomed to be lost in time. Ibn al-Quff, an apprentice of his, would maintain his teachings and go on to propose the existence of invisible connections between arteries and veins centuries before Malpighi would note capillaries using a microscope. Unfortunately, with the Western change to sea routes, the Middle Eastern economy strained terribly enough that civil strife and political unrest were shaking the libraries of the time. They opted more for conservatism and maintaining the status quo when there wasn't funding or freedom to consider building new theories. With the great sacking of cities and great fires that ensued, you can imagine that wealth of knowledge stagnated before turning to wisps in a blaze.

The pulmonary loop deduced by Ibn al-Nafis

Close enough to be spoken of in the same breath was India. Much like Ancient China, they knew that blood flowed continuously within the body and similarly it was understood through a systemic and energetic view instead of fluid dynamics. The Sushruta Samhita and Charaka Samhita were foundational Ayurvedic texts that described a closed, continuous distribution system driven by the heart, structured around the Seven Dhatus (Tissues). Blood (Rakta Dhatu) was classified as one of seven fundamental tissue layers. The heart was viewed as the central organ that propelled Rakta (blood) and Rasa (plasma/nutrient fluid) outward through vessels called Siras (veins/channels) and Dhamanis (arteries) to continuously nourish every part of the body. The texts noted that blood flow was driven by Vata (specifically Vyana Vayu, the subtle physical force governing systemic movement and heart contraction), describing blood as perpetually pulsing outward from the heart and returning through channels. Now here's the kicker. They knew all this, but they were constrained by ashoucha taboo, analogous to the Greco-Roman nekros taboo against touching corpses. This is where we witness the brilliant mind of a man in pursuit of answers where the law stifle any efforts. Sushruta specified using the body of a person who had not died of poison, prolonged disease, or extreme old age, ensuring the internal structures were intact to meet purity rules. He then had the body submerged for days in slow-moving water. The corpse was wrapped securely in grass, reeds, or inner bark and anchored inside a cage in a slow-flowing river, completely out of public view. Over seven days, the river water and natural bacterial action softened the skin and outer connective tissues without destroying the underlying structures. After this, the body was brought ashore, and instead of cutting it with knives, Sushruta and his students used coarse brushes made of bamboo bark, roots, and stiff grass to gently brush away the decomposed soft layers one by one. This cleanly exposed the major blood vessels, nerves, bones, and internal organs intact. He effectively pioneered observational anatomy and is generally considered the Father of Surgery alongside Al-Zahrawi as he also set to work inventing over 100 surgical tools. Despite their incredible surgical prowess, Indian medicine did not convert its anatomical observations into mathematical equations or closed-loop mechanical physics. Once Ayurvedic tradition codified this in its core theoretical framework that balanced the three Doshas (Vata, Pitta, Kapha) and the seven Dhatus, the medical system prioritised practical surgical skill, pharmacology, and holistic systemic balance over calculating exact blood volume per minute. This in my view would be a limitation from cementing a system too early.

The Sushruta Samhita is one of the earliest descriptions of anatomical dissections, written in the sixth century B.C.E.

With a look at these leading cultures of the age in medical discovery, you would find yourself asking why they siloed themselves and didn't just share knowledge. They could only stand to benefit from sitting in a room and trying to make sense of things together. However, you would be forgetting that these scientific discoveries and theories were rooted in their belief systems and philosophies. In that age where moral integrity and philosophical arrogance were at their height, you couldn't ask someone to simply make a Frankenstein system that did not function under a single unified canon of creation and existence. That is to ask you the modern seeker of answers, if you have been blinding yourself with dogma, ego and some such cloak caught on some thorny bush that is stopping you from progressing in your pursuit of knowledge.

 

Picture England, considerably wetter and greyer than any steampunk brass-and-goggles fantasy, but all the more convinced of their royalty's right to the world. What held together its medical faculties at the turn of the seventeenth century was unsurprisingly and overwhelmingly Galen. You don't go poking at the seams of dogma without getting called crazy, a heretic or disappearing. Into this hellscape of leeches, medical burning and half-cocked theories walks William Harvey, born in Folkestone in 1578, off to Cambridge, and then, wanting sharper teachers, to Padua. The same university that had made Vesalius decades before him. There Harvey studied directly under Hieronymus Fabricius ab Aquapendente, the anatomist who'd found something odd inside the veins: little pocket-shaped flaps. We now know them as valves. They seemed to stop blood pooling downward under gravity. Fabricius saw the doors in the wall and assumed they were like boulders in a stream, guessing they simply slowed the blood a little on its way to the limbs. He never quite asked which direction the blood was actually meant to travel.

William Harvey

Anywho, Harvey went home a physician of real standing, eventually serving two kings in succession. He was the consulting physician to James I from 1618 and later the personal physician to Charles I from 1625 which is its own tightrope walk. I mean, imagine keeping a monarch alive while quietly building a theory that made his own teachers and the widely held beliefs of the realm look outdated. Just rebuke the king to his face, will you? He first floated the idea in front of the Royal College of Physicians as early as 1616, in his Lumelian lectures, then spent a further decade gathering nerve, evidence, and dissected animals before he dared commit it to print. That book landed in 1628: Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus, “An Anatomical Exercise on the Motion of the Heart and Blood in Living Beings,” mercifully shortened by history to De Motu Cordis. Seventy-odd pages. Flimsy even, yet arguably the single most consequential pamphlet in the history of medicine. Its argument was this: blood is not manufactured fresh by the liver and burned up by hungry tissue with tides coming in and going out as Galen and 1500 years of this society would have it. Blood goes around. One continuous loop, pushed by a muscular pump — the heart.

A pamphlet to change the world

Here's where Harvey parts ways with everyone we've met on this tour so far. The Chinese physicians felt the truth of it in a wrist pulse and folded it into a cosmology of rivers and seasons. Ibn al-Nafis, centuries earlier, reasoned his way to pulmonary circulation with nothing but the sharpest kind of close reading, picking apart Galen's invisible septal pores without lifting a blade. The Ayurvedic surgeons watched Vata drive blood outward and back and rightly called it a closed system. Closed by the logic of life-force, not hydraulics. Harvey doesn't reach for a river metaphor or a subtle wind. Harvey reaches for arithmetic. Contemporary of Galileo flex!

 

He estimated, almost embarrassingly plainly, how much blood the heart ejects in a single beat, multiplied it by the beats in an hour, and landed on a volume of blood that outweighs the entire human body several times over. No liver, fuelled by some philosopher's stone, is turning that much blood over from breakfast alone. With that logic in hand, he naturally discovered shapes: “there must be a motion, as it were, in a circle.” Something was being reused, not endlessly manufactured and spent. To actually watch the mechanism, Harvey needed slower hearts than a frightened mammal's. Cut into a warm-blooded animal and its heart is a blur, contracting far too quickly for a seventeenth-century eye to follow. Cut into something cold-blooded instead — a snake, a dying eel, a toad in a cool room — and the heart, sluggish, will obligingly perform its systole and diastole close to slow motion. With this setup, he made the mechanical observation that the heart is simply a muscle whose job is to squeeze, to actively contract, chamber after chamber, and shove blood forward.

 

To illustrate his ideas further, he modelled experiments. Tie a ligature moderately tight above the elbow and the veins below swell up, dotted with small visible knots. These being the same valves Fabricius had noticed and shrugged off decades earlier. Run a finger along the vein toward the heart and it empties easily. Try to push that trapped blood the other way, away from the heart, and it simply won't go, stopped dead by the very same valve. Fabricius had found the door and assumed it was decoration. Harvey realised it was a one-way entryway — proof that venous blood travels toward the heart, full stop. Paired with arterial blood pulsing outward, that gave him the whole loop. Blood is pumped out through the arteries, back through the veins, around and around, with the heart sitting at the centre of it.

Image of Harvey’s experiment showing the swelling veins in the arms after ligation

All this, yet he couldn't quite find the connections between arteries and veins to close his system and he knew any detractor would feast on his liver on that point. So he did something unfashionably honest for a man under attack. He stated that such connections had to exist, purely on logic, and left the actual seeing of them to somebody else, someday. Hmm, this has the whiff of some Ibn al-Quff, working in Damascus centuries earlier who insisted on invisible links between arteries and veins on nothing but deduction. Neither man got to check his own answer key. That honour went to Marcello Malpighi, squinting down a microscope at a frog's lung in 1661, thirty-three years after Harvey's book. He watched blood cross from artery to vein through vessels too fine for any eye before his to have caught.

Harvey's closed system of blood flow colourised

You'd think a theory this thoroughly worked out would be lauded and accepted as new gospel. Instead, Harvey spent a good stretch of his later career being quietly needled by men who felt somehow personally slighted by his “disrespect” of Galen. Huff and Puff. Look at this upstart proving our history wrong. Is my whole life a lie? By most accounts, Harvey's own practice took a real hit after publication too. Patients grew uneasy handing their pulse to a man who'd just told the entire medical establishment it had been wrong for a millennium and a half. Another echo, no? Be right too early, and the world resents you for the inconvenience of it or, if you're Al-Nafis, you could be forgotten like a Ts and Cs agreement.

 

So what did Harvey actually leave physiology and medicine? Strangely, not a cure. The therapeutic playbook barely shifted. Doctors kept right on bleeding patients for another century or two afterward, since knowing that blood circulates doesn't automatically tell you it's bad to remove some of it. What changed for good was the standard of proof a theory of the living body was expected to clear. It was no longer enough to wrap an idea neatly into a cosmology, or lean on a dead Greek's authority. A claim about the body now had to survive vivisection, arithmetic, and a ligature tied round somebody's actual arm. That's the moment physiology stops being philosophy that happens to mention the body, and starts becoming an experimental science. This pulse, this beat, is the direct ancestor of every cardiologist listening through a stethoscope today.

 

And maybe that's the fairest place to close out this whole tour of the heart. Han China, Baghdad, the banks of the Ganges, and finally one stubborn Englishman (sadly not in New York. I know. It stings) with a scalpel and a ligature all arrived, independently, at more or less the same conclusion. Blood moves in a loop, and it doesn't run out. What separated them was never the destination. It was what each was willing to accept as proof of having arrived — a philosophy of rivers, a piece of pure deduction, a life-force pulsing outward, or, in Harvey's case, a number that simply refused to lie. So —what proof are you willing to accept, and what are you willing to go without, in reaching your own answer? An absence of proof was never proof of absence.

 

Till next time, fellow overgrounder!