Just for kicks, I looked up a few links about "thumos."

Came up with this.

It seems to me that ideally one needs a balance of forces. I remember the Star Trek episode where Kirk was split into two halves of his personality. One mild and reasoned, the other unrestrained and barbaric. The obvious storyline would have been to show the latter as "evil," and needing to be subdued. But as it developed it wasn't that simple. The "Dr. Jekyll" half was missing something critical required to command a starship. "Thumos?"

I haven't read Stevenson's "Dr. Jekyll and Mr. Hyde" for a while, but I think it also developed that the "dark" and "light" sides were both inadequate for survival on their own.

Plato is even more complicated.

There's a lot more, but that's about as far as I want to go with this.