were traded all the way from Beijing to Delhi, and from Baghdad to Constantinople.

In the next episodes, we're going to dive into how some specific kinds of knowledge

evolved over time.

First up: healing.

The history of medicine is about two of our big questions: one, what is life?

What makes it so special, so fragile, so… goopy!?

Two, how do we know what we know?

Why should I take my doctor's advice?

Why are deep-fried Oreos bad for me?

It may be tempting to look at medicine as a science that has simply progressed over

time—that medicine used to be bad, and its history is a story of how it got better.

And don't get me wrong: we love modern medicine!

You'll have to take my word for it until “Crash Course: Deep-Fried Everything”

drops, but the science behind lipid transport is just fascinating.

Focusing on progress, though, obscures what worked in the past.

Ancient and medieval medicine worked for millions of people.

They understood their bodies as bounded by rules.

And regardless of what worked, early medical systems allowed people to make sense of bodies

and health.

You may think that medicine is a technē, or practically oriented knowledge.

But today, we're going to focus on systems of medicine as world-ordering theories, or

epistēmē.

These theories were built up into a textual tradition, in which doctors wrote down what

they saw and cited earlier doctors when explaining their treatments.

So let's turn to medical education.

What textbooks would a would-be doctor read in a given place and time?

[Intro Music Plays]

Let's say you lived in Song Dynasty China: you'd study machine-printed textbooks on

traditional Chinese medicine, or TCM.

In this system, humans are small pieces of one vast organism called the Entire Dang Universe.

All things within this system are composed of five elements: fire, earth, metal, water,

and wood.

In TCM, health means a balance between two forces, yin and yang, representing dark and

light, femininity and masculinity, hot and cold, and so on.

Disease means imbalance.

Thus healthcare means restoring balance, in TCM, by manipulating the energy that flows

through living bodies, called qi.

You, the would-be doc, would learn all about how to move qi around using acupuncture and

acupressure, herbal therapies, exercise, and prescription diets.

If you lived in Gupta Dynasty India, you'd also get down with a five-element theory of

matter.

But you would study the science of life, Ayurveda.

You'd probably pick up the popular textbook Charaka Samhita, or one of the other samhita—or

“collections”—that could help you memorize hundreds of named body parts.

In addition to anatomy, the samhitas would also teach you etiology, or what causes different

diseases, and symptomatology, or what diseases look like.

When it came to treatment, your samhita would have information on the eight specialites:

the diseases of children, those of the elderly, mental diseases, diseases of the sense organs,

surgery, poisons and antidotes, and aphrodisiacs.

You would learn the five karmas or actions that were used for removal of toxins from

body tissues.

And, to prepare treatments, you'd learn a lot about plants, minerals, and animals.

But treating patients is only part of Ayurveda.

The science of life concerns healthful living in general, including how to prevent disease

and influence hygiene and diet.

What if you lived in, say, fourteenth-century Bologna, Italy—home to one of the oldest

universities in the world, which opened in CE 1088!

You would attend lectures, and you'd have a hand-copied textbook, not made by a press

as in Song China.

The medical theories in your textbook would be founded on Aristotelian biology and physics.

Bodies are composed of four special bodily humors.

Each of these corresponds to one of the four elements of Empedocles: blood, made of air,

phlegm, made of water, yellow bile, made of fire, and black bile, made of earth.

Illness is an imbalance in the humors.

Too much black bile, for example, causes depression.

Treatment means restoring the right humoral balance—like, with bloodletting.

When too much of one humor built up in the body, one way to restore a balance was to

let some of the excess drain off.

But the most common treatment, then as now, was simply offering good dietary advice.

Aristotle linked the four elements with the humors, but he wasn't a doctor.

The oldest nuggets of humoral wisdom in Western Eurasian medical textbooks were attributed

to a physician named Hippocrates of Cos, which means “Gregory House” in classical Greek.

We know something of his life—he died when Aristotle was in his teens—but we don't

have many surviving works by him.

What we do have is a collection of texts of various age and unknown authorship called

the Hippocratic corpus.

According to the corpus, Hippocrates I was a fan of the Pythagoreans.

(Remember, the secret math cult?)

But his skepticism—or doubt that certain knowledge is possible—set Hippocratic medicine

apart from a lot of Greek natural philosophy.

Hippocrates emphasized reason, observation, and medical prediction.

He emphasized that diet and the environment influence health, not the direct will of the

gods.

And his oath—“do no harm”—still underpins medical education.

Hippocrates was the Jimi Hendrix of Eurasian and North African medicine, innovating a new

style that challenged traditional ideas.

But Hippocratic physicians had to compete among many schools of healers.

It was a Roman named Galen who became medicine's Michael Jackson—the popularizer of a standard

humorism that would last until the 1800s.

Galen's system absorbed the smaller, uneven Hippocratic corpus.

Galen was born around CE 130 in Pergamon.

But he made his career in Rome, treating gladiators.

This gave him lots of experience peeking into the body while sewing up wounds.

Eventually he got the offer of a lifetime: court physician to Emperor Marcus Aurelius,

who was a battle-hardened general, Stoic philosopher, and all-around hardcore dude.

Galen wrote a huge number of influential texts—supposedly five hundred!

Though only eighty-three survive today.

These show that Galen built on the systems of Hippocrates and Aristotle, but also made

detailed notes on human anatomy drawn from experience.

He accurately observed how the larynx works and demonstrated the the lungs fill up with

air.

Oh ya, and he innovated cataract surgery.

But Galen definitely got some things wrong.

One reason is that human dissection was illegal in imperial Rome and the states that succeeded

it.

So a lot of anatomy was still guesswork based on observations of animals.

For example, dissecting sheep heads, Galen identified a circulatory organ called a rete

mirabile or “wonderful net” that is found in animals like sheep and dolphins… but

doesn't actually exist in humans.

After Galen, the most notable medical theorists in the Greater Mediterranean weren't Greeks

or Romans, but Arabs or Persians who had access to both Greek and Indian sciences.

First among was the Persian polymath Abū Bakr al-Rāzī —whose name also means “Gregory

House.”

Born in CE 854, al-Rāzī was prolific: he wrote dozens of books, including detailed

accounts of his cases.

He is considered by many historians to be one of the founders of several disciplines,

from psychology to opthamology.

And he was the first to describe smallpox and measles as distinct diseases.

Al-Rāzī also wrote for general audiences, educating them about health and disease.

Many of his works were encyclopedias based on Greek humoral medicine and natural philosophy.

His big one, al-Hawi al-Kabir or The Virtuous Life, was a large, influential medical encyclopedia.

Al-Rāzī was a unique dude who did exactly what he wanted.

Although he was one of the most scientific doctors of his time, he also wrote works of

Islamic prophetic medicine, al-tibb al-nabawi.

This discipline, an alternative to the Hippocratic–Galenic system, advocated traditional medical practices

mentioned in the Qur'an.

Al-Rāzī also influenced medicine by becoming the first fan of Greco-Roman humoral medicine

to beef with Galen!

He wrote a book called Shukuk 'ala alinusor—Doubts About Galen—in which he said that his own

observations contradicted some of Galen's claims.

Remember nullius in verba—“on the word of no one”—the motto of the Royal Society

of London, founded in 1660?

Al-Rāzī advocated this approach to medicine circa the year 900, over seven hundred years

earlier!

But, if you were really a medieval Italian medical student, the book you'd read probably

wouldn't be by Hippocrates, Galen, or al-Rāzī.

Instead, you'd read a translated encyclopedia featuring all of them.

In doing so, you'd participate in the scientific wonder called Scholasticism—or learning

through close readings of approved texts that recorded the observations and theories of

earlier thinkers.

Take it away, Thought Bubble!

One of the all-time greatest hits of medical education was al-Qānūn fī al-Ṭibb, or

The Canon of Medicine.

The Canon was written by another Persian polymath, Ibn Sina, born in 980.

Ibn Sina was widely seen as the best writer to summarize and comment on the Greco-Roman

doctors.

His Canon became one of the most important medical textbooks—and introductions to Aristotle's

physics—for six hundred years.

Your textbook is really a mashup of several different books.

Each page is like an onion: at its heart, one punctum or big idea by Aristotle, or Hippocrates

or Galen.

These are surrounded by layer upon layer of annotatio, or notes, by famous physicians

from distant cities such as Baghdad.

Your main throughline are the summaries by Ibn-Sina, whose name has been latinized as

“Avicenna”.

But there are notes by Latin translators such as Gerard de Cremona or Constantinus Africanus,

plus outer layers of notes by other medical students.

Maybe you even jot down your own.

Thus—way before WebMD—you're in conversation with doctors from all across space!

And time!

In universities such as Bologna or Salerno, you might also have access to another textbook,

this one by… wait for it… a lady!

Trota of Salerno wrote Practical Medicine According to Trota and Treatments of Women,

one of books of the The Trotula Ensemble.

This group of three texts from around 1200 traveled widely throughout medieval Europe.

The Trotula became foundational to gynecology and all other topics related to women's

health.

But you might not know that this foundational text on women's health was written by a

woman, because her identity was systematically written out of history until the late twentieth

century.

Because of course it was.

Thanks Thought Bubble!

So what was “life” for many educated people in Asia and North Africa between roughly 400

BCE to CE 1300?

Life was a universal property of which humans were just interesting examples.

Life was linked to the movements of special fluids, which were the objects of medical

treatments.

Life was ultimately built out of a smaller number of elements, and good health meant

balancing fluids and elements in the right way.

How did we know what life is?

For some physicians in classical Greece or imperial Rome, careful observation and comparison

to animals were crucial methods.

Persian doctors, influenced by both Greek and Indian ideas, synthesized earlier ideas,

expanded evidence for them, and challenged and reworked them.

Why did you, medieval citizen, trust this information?

Because books told you to!

And with that, dear student, we leave you to deal with… the Black Plague of 1347.

Bummer!

Next time—we'll deep-dive into the eternal question of “what is stuff” with a group

of thinkers who tried to “science” lead into gold—the alchemists.

Crash Course History of Science is filmed in the Dr. Cheryl C. Kinney studio in Missoula,

Montana and it's made with the help of all this nice people and our animation team is

Thought Cafe.

Crash Course is a Complexly production.

If you wanna keep imagining the world complexly with us, you can check out some of our other

channels like Scishow Psych, Animal Wonders, and The Art Assignment.

And, if you'd like to keep Crash Course free for everybody, forever, you can support

the series at Patreon; a crowdfunding platform that allows you to support the content you

love.

Thank you to all of our patrons for making Crash Course possible with their continued

support.