Looked again (on coffee break) into RS Crane, Languages of criticism and the structure of poetry (U. Toronto, 1953). This is the real deal, esp. the third essay ("The languages of contemporary criticism").

Seriously, this will change your way of seeing things.

If I have time to quote some passages, I will.

Aristotle saw things differently.

Crane shows how the standard method of 20th-cent. criticism was so pervasive, you couldn't se that there were other approaches.

The standard method assumed "poetry" is one big thing, a kind of discourse, and you defined "it" by differentiating it from other kinds of discourse (but all these kinds are still cousins : all "discourse", "language-usage").

Aristotle saw these very unique & specific activities which people did which came to be called "poetry". Tragic, comic, epic were sharply differentiated from one another, & from other genres. They weren't "modes of discourse" : they were forms of an art of imitation.

Then he investigates their structure & shape, to discover how they create that specific power & beauty he calls "imitation".

I'm really not succeeding here in transmitting Crane's very valuable insights.

The "art of imitation" (in dramatic/epic poetry) is structured, not with discourse, but upon the armature of plot.

[I know I'm repeating some things I tried to describe a few months ago. I'm just going back in that direction.]