By Paul Henry / in , , , , , , , , /

We’ve seen how, from around 400 BCE to CE
1300, ideas in astronomy, math, and engineering 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.

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