The Origin of Medicine: From Ancient Healing Practices to Scientific Medicine

In 18th-century BCE Babylonia, a surgeon who botched an operation had his hand cut off. Article 218 of the Code of Hammurabi spelled it out plainly: save the patient and earn ten silver shekels; kill the patient and lose your hand. Here is what makes this remarkable: around the time this brutal law was being codified, many of the treatments physicians used were incantations to drive out evil spirits. From this strange starting point where sorcery and punishment, experience and superstition were tangled together, it took thousands of years of trial and error to bring healing from the realm of the divine into the domain of human inquiry. And along the way, the most unexpected allies turned out to be alchemists chasing the dream of making gold.

The First Physicians: Healing Arts of Mesopotamia and Egypt

The history of medicine nearly coincides with the beginning of written records. The oldest known medical document discovered to date is a clay tablet unearthed from the Sumerian city of Nippur, dating to around 2200 BCE. This tablet records fifteen prescriptions containing treatments using oil, salt, milk, beer, and cinnamon.^[1]

Mesopotamian medicine was built upon a mystical worldview. The Babylonians believed that disease was caused by the wrath of the gods or by the invasion of evil spirits. Healers were divided into three types: the barû, who used divination to identify the cause; the āshipu, who drove out evil spirits through incantations and ritual; and the asû, who administered actual medicines and treatments.^[1] Remarkably, these three types of healers each maintained their own domain while also forming a cooperative system.

In the 18th century BCE, the Babylonian king Hammurabi codified laws concerning medical practice. Articles 215 to 223 of the Code of Hammurabi define the fees and penalties for physicians. A physician who successfully performed surgery on a free man received ten shekels of silver, but if surgery resulted in the patient’s death or blindness, the physician’s hand was to be cut off.^[2] This can be regarded as the world’s first medical legislation.

Meanwhile, ancient Egyptian medicine was even more systematic. The Ebers Papyrus, created around 1550 BCE, is a twenty-meter scroll containing 842 prescriptions and treatments. This document includes treatments for eye, skin, digestive, and dental diseases, as well as surgical treatment of tumors and management of fractures.^[3]

What is noteworthy about Egyptian medicine is the coexistence of magic and empirical observation. Alongside spells to drive out evil spirits, prescriptions featuring plants with genuine medicinal properties were recorded. The Edwin Smith Papyrus, dating to around 1600 BCE, is more secular in character. Addressing 48 cases of trauma, this document describes systematic examination, diagnosis, prognosis, and treatment procedures. Some scholars have called this papyrus the world’s first surgical textbook.^[3]

Hippocrates: Removing the Gods from Disease

In the 5th century BCE, a man born on the small Aegean island of Kos would fundamentally change the direction of medicine. Hippocrates (c. 460–370 BCE) is called the “Father of Medicine” today, but his true revolution was not the invention of new drugs. It was the exclusion of gods and evil spirits from the causes of disease.^[4]

The Hippocratic Corpus, a collection of texts left by Hippocrates and his disciples, consists of around sixty medical documents. In this corpus, Hippocrates addresses epilepsy, which was called the “sacred disease” of the time, and declares: “This disease is no more divine or sacred than other diseases. All diseases have both divine and natural causes.” He argued that epilepsy originated from an abnormality of the brain.^[4]

The cornerstone of Hippocratic medicine was humorism. The theory held that the human body is composed of four humors — blood, phlegm, yellow bile, and black bile — and that disease arises when the balance of these four humors is disrupted.^[4] Each humor was associated with a season, an age, and a temperament. Blood corresponded to spring and cheerfulness; yellow bile to summer and anger; black bile to autumn and melancholy; phlegm to winter and lethargy.

Humorism may appear unscientific to modern eyes, but it was revolutionary for its time. By explaining disease as a material imbalance rather than divine punishment, medicine became a subject open to observation and analysis. Hippocrates laid the groundwork for clinical medicine by meticulously observing patients, recording symptoms, and predicting prognosis. His methodology of patient observation, documentation, and prognosis remained the backbone of Western medicine for over two thousand years.^[4]

The name of Hippocrates lives on today through the Hippocratic Oath. The spirit of “First, do no harm (Primum non nocere)” continues as a central principle of modern medical ethics.

Galen: Medicine that Dominated a Thousand Years

In the Roman era, a figure emerged who compiled and expanded upon the Hippocratic system. Galen (c. 129–216 CE) was a Greek physician from Pergamon in Asia Minor who served as the personal physician to the Roman emperor Marcus Aurelius and was the foremost medical authority of his time.^[5]

Galen constructed a vast medical system based on the clinical experience gained from treating gladiators and extensive experiments in animal dissection. He was the first to demonstrate that arteries carry blood (previously it was believed they carried air), and he made important discoveries regarding the nervous system and brain function. Galen was also the first to prove that the larynx produces the voice.^[5]

However, Galen’s medical system contained critical errors. Since human dissection was prohibited in Rome, he primarily dissected monkeys and pigs, resulting in numerous incorrect descriptions of human anatomy in his writings. For instance, he claimed that blood was produced in the liver and traveled through invisible pores in the cardiac septum — a view entirely at odds with actual blood circulation.^[5]

The problem with Galenic medicine lay in its authority. After his death, Galen’s writings were venerated as the absolute truth of medicine. In medieval Europe, questioning Galen’s words was tantamount to heresy. This “shadow of Galen” dominated Western medicine for over 1,300 years, obstructing new discoveries.^[5]

The Islamic Golden Age: A Thousand Years of Hidden Light

Following the fall of the Western Roman Empire in the 5th century, European medicine was confined within monastery walls and stagnated. Yet during the same period, remarkable medical advances were being made in the Islamic world.

During the Islamic Golden Age of the 8th to 13th centuries, Arab scholars translated, synthesized, and advanced the medical knowledge of Greece, Persia, and India. The greatest physician of this era was undoubtedly Ibn Sina (980–1037 CE), known in the Latin-speaking world as Avicenna.^[6]

Ibn Sina, born in Bukhara in present-day Iran, demonstrated extraordinary talent — he was recognized as the personal physician of a king by the age of eighteen. The work he completed in 1025, the Canon of Medicine (Kitāb al-Qānūn fī al-Ṭibb), is a massive five-volume medical encyclopedia that systematically compiled the accumulated Greco-Roman-Islamic medical knowledge of its time.^[6]

What is astonishing about this work is its modernity. Ibn Sina articulated the principles of clinical trials for verifying drug efficacy and described the concept of contagious disease. He argued that soil and water could transmit disease, recognized that tuberculosis was infectious, and documented the influence of mental health on physical health.^[6] The Canon of Medicine was translated into Latin in the 12th century and served as the core textbook in European medical schools until the 17th century.

During the same period, Ibn al-Nafis (1213–1288 CE) was the first to accurately describe pulmonary circulation — the path blood takes from the heart to the lungs. This corrected an error of Galen and predated William Harvey’s discovery of blood circulation by more than 300 years.^[7]

Alchemy and Medicine: Unlikely Partners

In the late Middle Ages and Renaissance period, the most fascinating and paradoxical scene in the history of medicine unfolds. Alchemists who sought to make gold played a decisive role in laying the foundations of modern pharmacology.

Alchemy was not merely the art of making gold. Alchemists explored the fundamental principles of all things and studied methods to transform matter. In doing so, they developed a variety of chemical techniques — distillation, sublimation, purification, and dissolution. These techniques were later directly applied to drug manufacturing.^[8]

The link between alchemy and medicine began to form in the medieval Islamic world. The 9th-century Islamic alchemist Jabir ibn Hayyan (Latinized as Geber) was the first to describe sulfuric acid, nitric acid, and aqua regia, and he developed distillation apparatus. His contributions became the foundation of the chemical processes central to pharmaceutical production.^[8]

However, the figure who formally united alchemy with medicine was the Swiss physician-alchemist Paracelsus (1493–1541). Born Philippus Aureolus Theophrastus Bombastus von Hohenheim, he was a figure as enormous as his name suggests.^[9]

Paracelsus directly challenged the authority of Galen and Ibn Sina. When he began lecturing at the University of Basel in 1527, he taught in German rather than Latin, breaking with elitism. On the feast day of Saint John the Baptist that year, he burned the works of Galen and Ibn Sina in the town square, declaring: “Neither Hippocrates, nor Galen, nor Ibn Sina is your teacher. Even the down of my beard knows more than all of them.”^[9]

Paracelsus’s medical revolution rested on two central claims.

First, disease is essentially chemical in nature. He rejected humorism and argued that disease was caused by external chemical toxins (poisons). This can be considered a precursor to the germ theory of the 19th century.^[9]

Second, medicine must be chemical prescription. Paracelsus dismissed traditional herbal remedies and used metals and mineral compounds — mercury, sulfur, lead, iron, and copper — for treatment. His use of mercury to treat syphilis was revolutionary for the time.^[9]

Paracelsus proposed the concept of tria prima (three prime principles). He held that all matter is composed of three principles — sulphur (combustibility, spirit), mercury (fluidity, transformation), and salt (solidity, permanence) — and that an imbalance of these three causes disease.^[9] Though expressed in the language of alchemy, this theory actually pioneered a new field called iatrochemistry (chemical medicine).

Another vital insight of Paracelsus was the principle that dosage determines toxicity. “All things are poison and nothing is without poison; only the dose makes a thing not a poison (Alle Ding’ sind Gift und nichts ohn’ Gift; allein die Dosis macht, dass ein Ding kein Gift ist).”^[9] This maxim remains a fundamental principle of modern pharmacology and toxicology to this day.

Paracelsus received little recognition during his lifetime. He died in Salzburg in 1541, largely forgotten. Yet within a century of his death, his ideas formed the new school of iatrochemistry and transformed medicine. The iatrochemists of the 17th century carried on the Paracelsian tradition, developing new drugs through distillation, extraction, and purification. In this process, the alchemist’s laboratory became the prototype of the pharmaceutical research laboratory.^[8]

The Anatomical Revolution: Vesalius Dissects Galen

The year 1543 was doubly revolutionary in the history of science. In the same year that Copernicus published his work on the revolutions of the celestial spheres, the young Flemish physician Andreas Vesalius (1514–1564) published De Humani Corporis Fabrica (On the Fabric of the Human Body).^[10]

Vesalius taught at the University of Padua and practiced the method of directly dissecting the human body himself. At the time, anatomy lectures followed a fixed structure: a professor sat on a raised platform reading from Galen’s texts, while a barber-surgeon cut open the cadaver and students observed. Vesalius overturned this arrangement and picked up the scalpel himself.^[10]

De Humani Corporis Fabrica described the human body across seven volumes — from the skeleton to the nervous system — in meticulous detail, and included precise anatomical illustrations drawn by students of the painter Titian. Above all, this work directly pointed out more than 200 errors in Galen.^[10]

For example, Galen had claimed that minute pores in the cardiac septum allowed blood to pass through. After countless dissections, Vesalius confirmed that no such pores existed and declared Galen wrong. This single declaration set the stage for William Harvey’s subsequent discovery of blood circulation.^[10]

The resistance from Galen’s followers at the time was fierce. Some scholars put forward the absurd argument that such pores had existed in Galen’s time but that humanity had changed and they had since disappeared. Nevertheless, Vesalius’s anatomy established an empirical methodology in medicine — one of direct observation and verification — and this became an irresistible tide.

Blood Flows: Harvey and the Discovery of Blood Circulation

If Vesalius corrected the anatomical errors of Galen, William Harvey (1578–1657) demolished Galen’s physiology altogether. In 1628, Harvey published Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus (An Anatomical Study of the Motion of the Heart and Blood in Animals).^[11]

Harvey’s central finding was simple but revolutionary. The heart pumps blood in one direction, and the arteries and veins form a single closed circuit. He calculated the volume of blood expelled by the heart with each contraction and presented the mathematical argument that this volume was too great to be constantly produced anew by the liver. Blood, therefore, must circulate rather than be consumed.^[11]

This discovery completely overturned Galen’s theory of blood production — the notion that blood manufactured in the liver was consumed at the extremities of the body. Harvey’s discovery demonstrated the value of experiment and mathematical reasoning in medicine and heralded the beginning of modern physiology.^[11]

The Discovery of Bacteria: The Microscopic World Opened by the Microscope

In the mid-17th century, the Dutch cloth merchant Antonie van Leeuwenhoek (1632–1723) had a hobby of grinding lenses to inspect the quality of fabrics. He developed a simple microscope to achieve magnifications of over 270 times and used this lens to observe bacteria and protozoa for the first time. He called these tiny organisms “animalcules.”^[12]

Leeuwenhoek’s discovery was not immediately applied to medicine. The mere knowledge that microorganisms existed did not straightforwardly lead to the conclusion that germs cause disease. That connection was made by two scientists in the 19th century.

French chemist Louis Pasteur (1822–1895) refuted the theory of spontaneous generation in the 1860s, demonstrating that microorganisms entered from outside. He showed that fermentation and putrefaction were caused by microorganisms and developed the heat treatment method for killing them — pasteurization. He went further and developed vaccines for chicken cholera, anthrax, and rabies.^[12]

German physician Robert Koch (1843–1910) connected Pasteur’s research to clinical practice. He was the first to prove that the anthrax bacillus caused anthrax, and he discovered the bacteria responsible for tuberculosis and cholera. Above all, he formulated Koch’s postulates — logical criteria for proving that a specific bacterium causes a specific disease.^[12] These postulates became the methodological foundation of bacteriology.

The establishment of germ theory brought sweeping changes to medicine. British surgeon Joseph Lister (1827–1912) applied Pasteur’s germ theory to surgery, introducing antiseptic procedures using phenol (carbolic acid). Before this, mortality from post-surgical infection was as high as 45–50%; after the introduction of antiseptic surgery, it fell to below 10%.^[12]

The Completion of Modern Medicine: The Revolutions of the 20th Century

Between the end of the 19th century and the early 20th century, medicine advanced at an unprecedented pace.

In 1895, German physicist Wilhelm Röntgen discovered X-rays, enabling medicine for the first time to look inside the body without making an incision. Röntgen took an X-ray of his wife’s hand, clearly revealing the bone structure, and received the first Nobel Prize in Physics in 1901 for this discovery.^[13]

In 1928, British bacteriologist Alexander Fleming (1881–1955) made one of the most important discoveries in human history from a chance observation. Returning from a summer holiday, he found that a Staphylococcus culture dish left in his laboratory had been contaminated with blue-green mold (Penicillium), and that the bacteria surrounding it had died. This observation led to the discovery of penicillin.^[13]

Penicillin began to be produced on a large scale in the 1940s. Deployed on battlefields during World War II, it saved the lives of millions who were dying from pneumonia, syphilis, gangrene, and other infections. The age of antibiotics had arrived.^[13]

In the mid-20th century, Watson and Crick’s elucidation of the double helix structure of DNA (1953) took medicine down to the molecular level. This became the starting point for a long journey leading to genetic medicine, biopharmaceuticals, and the genomic medicine of the 21st century.^[13]

Conclusion: Healing Becomes Science

From the prescriptions inscribed on Sumerian clay tablets to the mRNA vaccines of today, the history of medicine is a record of humanity’s unceasing effort to understand its own body.

The most decisive turning point in this journey was the transfer of healing from the domain of the divine to the domain of human inquiry. Hippocrates’s observations, Ibn Sina’s systematization, Paracelsus’s chemical challenge, Vesalius’s dissections, Harvey’s experiments, and the germ theories of Pasteur and Koch — all were steps in that transformation.

In particular, the transition from alchemy to iatrochemistry is the most paradoxical scene in the history of medicine. The fanciful dream of making gold was transmuted into the practical art of making medicine. Modern pharmacology bloomed from the ashes of the books Paracelsus burned in the town square.

The Babylonian physician who risked losing his hand to pick up the scalpel, Paracelsus burning Galen’s books in the town square to challenge established authority, Fleming stumbling upon blue-green mold on a neglected culture dish — all were driven by the same fundamental impulse: the urge to understand what is unknown, and the tenacity to use that understanding to reduce suffering. Paradoxically, the moments when medicine leaped forward most dramatically were almost always moments when an old certainty was admitted to be wrong. Each time a dogma crumbled — the belief that gods sent disease, the conviction that humors explained everything, the orthodoxy that blood was manufactured in the liver and consumed at the extremities — medicine advanced another step. Perhaps the true engine of medicine was never new discovery, but the courage to discard old error.