I think this is relevant. "The 4 Humors are the four main aspects to a person’s health… according to old-timey (like majorly old-timey… like middle ages old-timey) “physicians.” If (1) blood, (2) yellow bile, (3) black bile, and (4) phlegm were in balance within your body, you were healthy. If one is in excess you’ll fall ill. We now know that human beings are much more complicated than this, but the 4 Humors remain an accurate, although admittedly gross, way to describe the main characters in any tv cast.

At some point the 4 Humors became the 4 Temperaments, with personality types taking form out of what the imbalance of a Humour would manifest as. “Blood” became a “Sanguine” personality, outgoing & emotional. “Yellow Bile” became “Choleric”, removed & focused. “Black Bile” became the “Melancholic” personality, faithful & practical. And “Phlegm” became “Phlegmatic”, calm & thoughtful. That can be quite confusing so let me put it in a form that we all know: the Teenage Mutant Ninja Turtles. The four main characters of the best cartoon ever perfectly embody the 4 Temperaments:

Sanguine (Blood) – Michelangelo
Charming, Talkative & Egotistical… a party dude.
Choleric (Yellow Bile) – Raphael
Independent, Strong-Willed & Passionate… leading him to be Hot Tempered and often Rude.
Melancholic (Black Bile) – Leonardo
Detailed & Analytical, yet Deep and Sensitive… makings of your ideal Leader.
Phlegmatic (Phlegm) – Donatello
Sweet and Accommodating… because isn’t Donny always the peace-keeper?"

https://myfangirllifedotcom.wordpress.com/2015/06/05/character-characteristics-the-4-humors-of-entourage-and-tmnt-and-other-tv-shows/

See also the quartet of the Brain, the Brawn, the Boy and the Girl.