Poetry 1-Definitions

I am taking a class in Greek Literature this semester and we had a very interesting discussion in class recently about poetry. We were asked to define it. The professor wanted us to talk about it, and then think about it over the next fifty-years or so. But ... Lets do this now.

So, what is a definition, what are we being asked to do with poetry? A definition is simply identification, it means stating explicitly that this is this as opposed to that. So in defining something we first need to narrow down what we're talking about, and then we need to state how it is different than everything else. That is why I think Aristotle is correct in saying that a definition is both a genus and a differentiae. For example, when you ask 'what is man, how do you define it?' you first narrow down what you're talking about from everything that exists to a specific category of things that exist of which man is a part (similar/related to, but not wholly compromising). This is the genus, and in this case the genus is 'animal'. Man is an animal, but not the animal. I don't see why you couldn't use a more or less specific genus, why this is the certain level of genus that one must use, but it would take a more thorough study of concepts than is necessary now to answer that.

Anyway, now the important part is stating what it is that makes this animal, man, different than any other animal. This is called the differentiae, and I think it is the most important, most difficult part of a definition because you must identify the causal trait, or as I call it 'defining characteristic', that makes it this and not that. For every individual object there are many numerous ways to describe it, characteristics, but it is the job of the definer to identify which one causes it to be a part of this concept and not another. For the concept 'man' the defining characteristic is reason, ergo --> man is the reasoning animal, it is an animal which reasons as opposed to any other animal.

So far this is my understanding of definitions and I do not think it is yet complete.