Full Idea
Is the third element of the mind a form of reason, so that there are only two elements to it, reason and appetite? There must be a third element, if spirit ('thumos') can be shown to be distinct - and you can see it in children when they are born.
Gist of Idea
There is a third element to the mind - spirit - lying between reason and appetite
Source
Plato (The Republic [c.371 BCE], 441a)
Book Reference
Plato: 'Republic', ed/tr. Waterfield,Robin [OUP 1993], p.152
A Reaction
This is Plato's famous tripartite doctrine of the soul, though in other dialogues he says that there is only reason and appetite. The suspicion is that he fixed the soul having three parts, to match the three parts of his republic's social structure.
Related Idea
Idea 22582 Spirit [thumos] is the capacity by which we love [Aristotle]