Short answers, pulled from the story.
Hippocrates identified blood, phlegm, yellow bile, and black bile as the four specific bodily fluids. These substances dictated both physical health and behavioral patterns within the body.
Galen of Pergamum lived from 129 AD to 201 AD and transformed humoral theory into a dominant medical doctrine. His authority ensured his version became the standard for over a millennium.
Avicenna published The Canon of Medicine in 1025 during the Golden Age of Islam and summarized the four humors and temperaments into a structured table. His work preserved Greek knowledge while adapting it to new cultural contexts for Persian and Arab physicians.
The theory of humorism fell out of favor in the 17th century as cellular pathology emerged and provided evidence against the existence of named bodily fluids causing disease. Advances in chemistry and microbiology definitively disproved the core premise by the mid-19th century.
Elizabethan playwright Ben Jonson wrote humor plays where character types reflected their humoral complexion. In The Taming of the Shrew, Petruchio used humoral therapy techniques on Katherina to balance her choleric nature with colder environmental factors.