Full Idea
Plato makes psychic conflict intelligible by appeal to a conception of the soul such that the soul is closely connected to the body at the level of appetite and relatively separate from the body at the level of reason.
Gist of Idea
Psychic conflict is clear if appetite is close to the body and reason fairly separate
Source
report of Plato (The Republic [c.374 BCE], 339b) by Deborah K.W. Modrak - Classical theories of Mind
Book Reference
'Encyclopedia of Classical Philosophy', ed/tr. Zeyl,Donald J. [Fitzroy Dearborn 1997], p.345
A Reaction
I'm not sure about this at the level of biology or ontology, but at the phenomenal level this is obviously right. Hunger makes consciousness feel like a physical event, but doing arithmetic doesn't seem remotely physical.