The outdated and disproven theory of Humorism has a long history, dating back to Ancient Egypt. Even though the theory has been discredited, it still influenced western medicine for over 2,000 years, and many different cultures drew from it. The theory holds that that the human body is host to four basic ‘humors’, which when balanced to ensure a persons health. Sending these substances out of balance are the cause of all diseases and defects according to the theory. The humors were in order: Black Bile, Yellow Bile, Phlegm, and Blood. Each one of these humors corresponded with a different season of the year, as well as an element found in nature.
The Lost World by Michael Crichton page 415 (First Edition, Thirty Fourth printing)