Great IdeasNature and science
The body, health and medicine
How the body works and how healers learned to help it.
The question
How does the body work, and how did healers learn to understand it and help it heal?
How the books answer
Oldest first. Each stop is our own short summary of what the author argued; follow the link to the rung for the whole lesson.
late 5th and 4th centuries BC
Hippocrates and his school, The Oath, On Ancient Medicine, On Airs, Waters, and Places, Aphorisms, The Sacred Disease, and other works
The Hippocratic writers insisted that diseases have natural causes, even epilepsy, which many called sacred. They watched patients carefully, noted the effects of climate, water and diet, and wrote down what they saw. The Oath bound doctors to help the sick and do them no harm.
“It is thus with regard to the disease called Sacred: it appears to me to be nowise more divine nor more sacred than other diseases, but has a natural cause from which it originates like other affections.”
c. 350–322 BC
Aristotle, History of Animals, Parts of Animals, Motion and Gait of Animals, Generation of Animals
Aristotle dissected animals and described their organs carefully. He watched a chick develop in the egg day by day and saw the tiny heart beating. He thought the heart, not the brain, was the center of feeling, which later anatomists corrected.
“This point beats and moves as though endowed with life.”
late 2nd century AD
Galen, On the Natural Faculties
Galen, a doctor to gladiators and emperors, did experiments on animals to learn how organs work. By tying off the tubes from the kidneys, he showed that urine is made in the kidneys, not the bladder. His writings guided medicine for over a thousand years, mistakes and all.
1580–1595
Michel de Montaigne, Essays
Montaigne, who suffered from kidney stones, was skeptical of the doctors of his day, whose remedies often did more harm than good. He preferred to let nature take its course and to watch his own body. His doubts show how uncertain medicine still was.
1628; the letters On the Circulation of the Blood, 1649
William Harvey, On the Motion of the Heart and Blood in Animals, and On the Circulation of the Blood
Harvey shows that the heart is a pump and that blood circulates around the body, out through the arteries and back through the veins. He used dissection, experiments, the valves in veins and simple arithmetic. It overturned Galen's view that blood is made and used up.
“Now this I afterwards found to be true …”
Go to the rung: Harvey: On the Motion of the Heart and Blood
1651
William Harvey, On the Generation of Animals
Harvey turns to how animals develop. Studying chicks and deer, he argues that all animals begin from an egg of some kind and that parts form one after another. He could not see the cell, but he set the questions for later embryology.
“An egg is the common origin of all animals.”
1899 (dated 1900)
Sigmund Freud, The Interpretation of Dreams, with the early papers
Freud, a doctor of the nerves, tried to treat illnesses of the mind by talking with patients about their memories and dreams. He started a whole field of talk therapy. Later research rejected many of his theories, but the idea that talking can help some troubles of the mind lives on in other forms.
For young readers
Long ago, people sometimes thought sickness was caused by angry gods. Hippocrates, a Greek doctor, said no: illness has natural causes we can study, like bad water or bad food.
Later, William Harvey discovered that your heart is a pump that sends blood all around your body in a loop. Put two fingers on your wrist and feel your pulse: that's your heart pumping!
Talk about it
- Why was it important to say sickness has natural causes?
- Feel your pulse. Can you find it on your neck too?
- The doctors' oath says first do no harm. Why is that a good rule?
- Galen made mistakes that lasted 1,000 years. How do mistakes get corrected in science?
Where else on the site
- The Heart and Blood
- The Path of Blood
- The Kidneys and Water Balance
- Systems Working Together
- Helpful and Harmful Microbes
- Hypotheses and Controlled Experiments
Every rung tagged with this idea:
These pages are our own short synthesis, written for families. They were inspired by Mortimer J. Adler's Syntopicon, the index of great ideas in volumes 1 and 2 of Great Books of the Western World, but the questions, summaries and groupings are ours, not the Syntopicon's. Short excerpts come from public-domain translations, credited where they appear.