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Starvard University · History of Medicine
How did doctors learn, one hard discovery at a time, what actually makes people sick and what actually helps? Follow Sir William Osler on his flight across the centuries, from temple sleep and the four humors to the circulation of the blood, the first vaccine, and the germ theory.
Hello, my name is Finn, and I'm going to help you understand this course.
Here it is, explained like you are 10:
Long ago, doctors thought illness came from angry gods or from four juices in the body getting mixed up wrong. Then, slowly, brave people started looking carefully, testing ideas, and writing down what they really saw. A man proved the blood goes round in a circle. Another stopped a terrible disease with cowpox. This course tells those true detective stories.
Sir William Osler (1849 to 1919) was a Canadian physician who taught at McGill, the University of Pennsylvania, and Johns Hopkins, and finished his career as Regius Professor of Medicine at Oxford. He changed how doctors are trained by taking students out of the lecture hall and into the ward, to learn at the bedside of real patients. His lectures on the evolution of modern medicine, delivered at Yale in 1913 and published in 1921, are our spine for this course.
One honesty note runs through everything that follows. This is a history course, not medical advice. Osler wrote before antibiotics, before most vaccines, and before much of modern surgery, and he knew the story was unfinished. Where old practice has been left behind, like bloodletting and the four humors, we say so plainly. What survives from these old doctors is not their remedies. It is their way of looking: observe carefully, test the idea, and admit what you find.
The whole course in brief
What you will be able to do after this course
The eight lessons
Lesson 1
For most of human history, being sick was frightening and mysterious, and medicine was a mix of everything people could think of: prayer, charms, dreams, herbs, surgery, and shrewd observation, all stirred together. In Egypt and Babylon, priest physicians treated disease as the work of gods or demons, yet the same cultures kept careful written records of injuries, fevers, and remedies, and some of those remedies were sensible. A broken bone was splinted. A wound was cleaned and dressed. The rest was guesswork dressed in ritual, because nobody yet knew what a body was doing inside, and nobody had a method for finding out.
Sir William Osler opens his lectures by calling his survey, in a letter quoted by his editors, "an aeroplane flight over the progress of medicine through the ages". It is a good image for this first lesson. From the air you can see the pattern of the early centuries: medicine begins wherever suffering is, it gathers real experience at temple shrines and on battlefields, and it also gathers error, because a remedy that seems to work once, on a patient who would have recovered anyway, can be believed for a thousand years. Without controlled tests, there was no reliable way to separate the remedy that helped from the recovery that merely followed it.
Hold on to one distinction before we go further, because this whole course depends on it. This is history, not medical advice. We will meet treatments in these lessons that no modern doctor would use, and we will say plainly when practice has moved on. What the early healers give us is not their prescriptions. It is the beginning of a habit: watching the sick closely, remembering what happened, and passing the record on. That habit, slowly sharpened, is what eventually turned medicine into a science.
Lesson 2
Hippocrates of Cos, who lived in the fifth and fourth centuries BC, is called the father of medicine, though Osler is honest that the man himself is shadowy and that the writings bearing his name came from a whole school. What matters is the turn those writings took. They treated disease as a part of nature, to be watched and described like weather. On epilepsy, long called the sacred disease, the Hippocratic writer insisted, as Osler quotes him: "It appears to me to be no wise more divine nor more sacred than other diseases". Each sickness, the school argued, has its own nature and its own natural cause.
The Hippocratic method was careful observation. Case histories in these writings note the day a fever rose, when it broke, what the patient ate, and how the illness ended, success and failure alike. Osler admired the honesty of a surgical writer who recorded his unsuccessful experiments and the reasons for them, believing that knowing why something failed was valuable knowledge. The school also trusted nature power to heal, the vis medicatrix naturae, and saw the doctor job as helping that power rather than fighting it with violent interference. Rest, food, fresh air, and time did much of the work, which was often safer than the heroic treatments invented later.
The famous oath sworn in Hippocrates name asks a doctor to keep patients from harm and injustice, to guard confidences, and to teach the art freely to the next generation. Doctors still swear versions of it today, updated for a changed world. The school also gave medicine the theory of the four humors: blood, phlegm, yellow bile, and black bile, whose balance meant health and whose imbalance meant sickness. That theory was wrong, and it would mislead medicine for two thousand years. But the observation habit was right, and it is the half of Hippocrates that never died.
Lesson 3
Galen, born at Pergamon in AD 130, was, in Osler telling, observer, experimenter, and philosopher in one energetic man. He tended gladiators wounds in his home city, lectured on anatomy in Rome, treated the emperor Marcus Aurelius, and wrote so much that his works fill shelf after shelf. Because human dissection was barred, he learned anatomy from animals, especially apes and pigs, and mapped what he found onto the human body. Much of it was brilliant. Some of it, the liver made of lobes like a dog liver, or tiny pores in the wall of the heart that no one could see, was wrong, and the errors hardened into doctrine.
Galen built the humors into a complete system: temperaments, qualities of hot and cold, wet and dry, and a pharmacy of hundreds of drugs matched to each imbalance. A system that explains everything is very hard to dislodge, and Galen had a second advantage: authority. After his death, medicine in Europe shrank through plague, war, and the fall of Rome. Monasteries copied his books. Arab and Persian physicians, including Avicenna, preserved, organized, and extended Greek medicine when much of Europe could not. For well over a thousand years, to study medicine was largely to study Galen, and to question him felt like questioning medicine itself.
The long Middle Ages were not empty of care. Monasteries ran infirmaries, cities built hospitals, and the medical school at Salerno taught students for centuries. But the method had inverted Hippocrates: the book came first, and the body was expected to agree with it. Bloodletting, prescribed to rebalance the humors, became a routine answer to fever and inflammation, and it stayed routine long after it should have been tested and dropped. It has ended now, and good riddance: the germ theory and real physiology replaced the humors entirely. The lesson of Galen age is sobering. Brilliance plus authority, minus the habit of testing, can freeze a science for a millennium.
Lesson 4
William Harvey, an English physician trained at Cambridge and Padua, published his little book on the motion of the heart and blood in 1628, and it quietly demolished fourteen centuries of Galen. Galen had taught that blood was made in the liver, ebbed and flowed in the veins, and seeped through invisible pores from one side of the heart to the other. Harvey dissected living and dead animals, watched hearts beat in cold blooded creatures where the motion slows down, and tied ligatures on human arms to see which way blood actually moved in the veins, whose one way valves his teacher Fabricius had described but not understood.
His killing argument was arithmetic, and anyone can follow it. The heart, Harvey reasoned, expels a quantity of blood at every beat. Multiply even a modest quantity by the beats in half an hour and the total is far more blood than the body contains, and far more than food could supply. The liver cannot be manufacturing it fresh. As he concluded, the blood is "impelled in a circle, and is in a state of ceaseless motion". The heart is a pump, the arteries carry blood out, the veins bring it back, and the same blood goes round and round. Harvey never saw the capillaries that join the two systems; the microscope would reveal them to Malpighi a generation later, exactly where Harvey theory said a passage had to exist.
Be honest about the reception: Harvey contemporaries resisted him for decades. He was mocked as a circulator, a quack term borrowed from travelling mountebanks, and he complained that his practice suffered after the book appeared. Galen authority, university teaching, and simple habit all pushed back. Harvey answered with experiments anyone could repeat, and in the end repetition won. That is the pattern to remember. A new truth in medicine does not triumph when it is announced. It triumphs when other people can test it, do test it, and get the same result.
Lesson 5
Smallpox was one of the great terrors of the eighteenth century: it killed perhaps one sufferer in three, blinded others, and scarred the faces of most survivors. Before Jenner there was already variolation, the deliberate infection of a healthy person with matter from a smallpox sore, hoping for a mild case and lifelong protection. The practice came to Britain from Constantinople through Lady Mary Wortley Montagu, who had her son inoculated abroad in 1718 and her daughter in London in 1721, and promoted it against fierce opposition. Variolation usually worked, but it could kill the person it meant to protect, and the inoculated could spread full smallpox to others. It was protection with a real price.
Edward Jenner, a country doctor in Gloucestershire, had heard the dairymaids saying that cowpox, a mild disease caught from cattle, protected them against smallpox. His teacher John Hunter had given him the famous advice, as Osler tells it: "Don't think, try!". In 1796 Jenner tried. In Osler summary of Jenner own words, "The first experiment was made upon a lad of the name of Phipps": James Phipps, aged eight, received matter from a cowpox sore on the hand of dairymaid Sarah Nelmes. Weeks later Jenner inoculated the boy with smallpox matter, and the disease did not take. He published his Inquiry in 1798.
Tell the story straight, including its rough edges. Jenner experiment on a child would not pass a modern ethics review, his early reception from the medical establishment was cold, and he spent years answering critics and supplying vaccine matter to the world, largely at his own expense. But the result held everywhere it was tested: vaccination, named from vacca, the Latin for cow, protected without giving smallpox itself. Within a few years it crossed oceans, and in 1980 the World Health Organization declared smallpox eradicated, the first disease in history ended by human effort. The road ran from a folk observation, through variolation and Montagu, to a testable experiment.
Lesson 6
Louis Pasteur was a chemist, not a doctor, and he came to disease through wine, beer, and silkworms. Studying fermentation, he showed that it is caused by living microbes, and that souring and putrefaction are the work of organisms carried in the air, not of spontaneous generation. His swan neck flasks, which let air in but trapped dust in the bend, stayed sterile until he tipped them, a beautifully simple experiment. From fermentation he moved to disease itself: silkworm epidemics, anthrax in sheep, and finally rabies, where his vaccine saved a boy named Joseph Meister in 1885. Germs, he argued, were not a symbol of disease. They were its cause, and each disease had its own.
Joseph Lister, a surgeon in Glasgow, read Pasteur and saw his own wards in the argument. Surgery in the 1860s could set a bone or remove a stone, but compound fractures and amputations routinely turned septic, and hospital gangrene and blood poisoning killed patients the operation had spared. Lister seized on Pasteur finding, quoted in the Harvard Classics volume, that the septic properties of the air depended not on its oxygen but on "minute organisms suspended in it". If germs caused putrefaction in a flask, they caused it in a wound. In 1867 he published his antiseptic method: carbolic acid dressings and scrupulous cleanliness to kill germs before they reached the injury.
The germ theory won, and it won the way Harvey truth had won: by results others could repeat. Lister wards stopped smelling of sepsis, and compound fracture patients who once faced amputation kept their limbs. Resistance was real at first; senior surgeons mocked the invisible germs and the carbolic spray, and Lister himself later gave way to the cleaner aseptic methods that grew from his own principle. But the argument was over in substance. Semmelweis handwashing, Pasteur microbes, Lister antisepsis, and Koch bacterial methods together ended the age of humors for good, and made modern surgery, and modern hospitals, possible.
Lesson 7
William Osler arrived at the new Johns Hopkins Hospital in Baltimore in 1889 and rebuilt medical training around a simple conviction: you learn medicine from patients, not only from lectures. Students in their later years left the classroom for the ward, took histories, examined patients, followed their illnesses day by day, and presented what they found. Osler took the German and Edinburgh habits he admired and made the teaching hospital ward the real school. He also built the residency system, in which young doctors live and train in the hospital under senior physicians for years, a pattern that medical training still follows around the world.
His manner was part of the method. Osler taught equanimity, his famous word for calm under pressure: a doctor who panics at a crisis, or who promises more than medicine can deliver, fails the patient twice. He was known for aphorisms short enough to remember at three in the morning, for his love of books and medical history, and for insisting that listening to a patient is a diagnostic instrument, since the patient is usually telling you the diagnosis if you let him finish. The bedside manner people praise in a good doctor today (unhurried, observant, honest about uncertainty) is very largely Osler manner, passed down through the doctors he trained.
Credit his limits plainly, as he would have wanted. Osler died in 1919, before antibiotics, before insulin was in general use, before most vaccines and nearly all of modern surgery. Much of what he could offer a pneumonia patient was nursing, oxygen at the end, and watchful care, and he knew the history he lectured on was not finished: he presented his own era as one more chapter, not the conclusion. He also held views of his age that have not aged well, and his famous farewell address was misreported into a scandal about old age that he never intended. The way survives the man: go to the patient, look for yourself, keep your head, and keep learning.
Lesson 8
You are not a medical student, so what is this history for? Start with humility, in both directions. Galen was no fool, and his system ruled for fourteen centuries; bloodletting was defended by learned men into the nineteenth century. Intelligent, sincere experts can be wrong for a very long time when a theory is elegant and nobody tests it. That should make a patient slow to trust any claim, old or new, traditional or fashionable, that rests only on authority, testimonials, or a famous name. The age of a remedy proves nothing: some old remedies are useless, some are dangerous, and a few turned out to contain real drugs that science later isolated and dosed properly.
The second lesson is what a good test looks like, because this history is a museum of them. Harvey counted. Jenner compared: the vaccinated boy, challenged with smallpox, did not fall sick. Pasteur tipped his flasks and let anyone repeat the result. Lister published his ward outcomes for other surgeons to check. When you meet a health claim today, ask their questions. Compared with what? Counted how? Could the patients have recovered anyway, as so many did under temple sleep and humoral dosing? A treatment that has never faced a fair comparison has not earned your confidence, however beautiful its story is.
The third lesson is trust, properly placed. Modern medicine is not right about everything, and its history, this course included, is full of resistance to new truth and of harm done with confidence. But it is the only tradition in this story that built self correction into its method: publish, replicate, revise, and abandon what fails, as humors and bloodletting were abandoned. Use it as Osler would advise. Ask your doctor what the evidence is, what the alternatives are, and what happens if you wait. Take the history you have just read as a patient charter: respect for careful observation, suspicion of untested certainty, and gratitude for the long line of people, from Cos to Baltimore, who learned to tell the difference.
Sources
This course is taught from three books, all free for anyone to read in full at Project Gutenberg.
Graduation
You travelled from temple shrines and the four humors to Harvey pump, Jenner vaccine, Pasteur microbes, and Lister antiseptic wards, and you finished at Osler bedside, where modern doctors are still trained. You now know how medicine learned to test its ideas, and how to ask the same questions of any health claim you meet. Congratulations, and may you always ask, compared with what?
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