I phrased it awkwardly. Simply put, in Ancient Greece, liver was something like heart in modern society. It was the seat of human emotions.
So by destroying Prometheus' liver, Zeus attempted to destroy his human emotions, including his pride and defiance against gods.
I don’t think it was phrased awkwardly, I was just curious.
Also, liver-toxic people are really angry / choleric, while healthy people are relaxed and composed, so there's something to that.
It was the believed area of emotion, passion and 'soul'. I think western/modern religion has morphed from the liver to the heart essentially.
This is still the normal in the middle east (and likely elsewhere)! In Turkey you call somebody dear to you "my liver" as a pet name.
There are a bunch of Japanese words (including a several loanwords from Chinese) that use the liver / gallbladder metaphorically for courage. Both derive from associations between the humours and personality / behavior. I have no idea, however, why both Eastern and Western naive psychology associate gall with, well, gall.
In Italian, to have 'liver' (fegato) means to be courageous.
You left out the important part, that Greek influence made it all the way to Japan, in some cases identifiably intact: "[The Greek wind god] Boreas became the Japanese wind god Fujin through the Greco-Buddhist Wardo/Oado and Chinese Feng Bo/Feng Po ("Uncle Wind"; among various other names). The mother deity Hariti [Kishimojin in Japan] was inspired by Tyche."
>I have no idea, however, why both Eastern and Western naive psychology associate gall with, well, gall.
Possibly because it's filled with strong acid.
Humors perhaps. Not my area, so I do not recall the correspondence ...