Key Terms You Must Know

📖 Key Terms You Must Know

Four Humours

The theory developed by Hippocrates (c.460-370 BC) that the body contained four liquids — blood, phlegm, yellow bile, and black bile — and that illness was caused by an imbalance of these humours. Treatment aimed to restore balance by removing excess humour (through bleeding or purging) or by adding what was lacking. This theory dominated medicine for approximately 1,400 years, from ancient Greece until the Renaissance.

Galen (c.130-210 AD)

A Roman physician whose medical writings became the unquestioned authority for over 1,000 years. Galen expanded the Four Humours theory and wrote detailed works on anatomy and physiology — but made significant errors because he dissected animals (especially pigs) rather than humans. The Church endorsed Galen's work as confirming God's design of the human body, making it impossible to question without risking accusations of heresy.

Miasma theory

The belief that disease was caused by "bad air" — foul-smelling vapours rising from rotting organic matter, swamps, cesspools, and decaying bodies. People who believed in miasma theory carried posies of flowers, burned herbs, and tried to avoid bad smells. While miasma theory was completely wrong about the cause of disease, it accidentally led to some helpful practices: cleaning up rotting waste that actually did harbour disease-carrying rats and insects.

Hippocrates (c.460-370 BC)

An ancient Greek physician often called the "father of medicine." He developed the idea that disease had natural causes rather than supernatural ones — a significant step forward from blaming gods entirely. He developed the Four Humours theory and emphasised observation of patients. His "Hippocratic Oath" — promising to do no harm — is still used by doctors today.

Bleeding (phlebotomy)

The main treatment for an excess of blood in the humours system. A doctor would cut a vein (usually in the arm) and allow blood to drain, or apply leeches to suck blood. Some patients did feel brief relief (possibly from reduced blood pressure), which seemed to confirm the treatment worked. In reality, excessive bleeding weakened patients and sometimes killed them.

Purging

Treatment for an excess of yellow or black bile. Patients were given strong laxatives or made to vomit. Like bleeding, this treatment was based on the humours theory and was generally harmful rather than helpful, especially for already weakened patients.