What is dialectic?

I wanted to elaborate what I was beginning to get at in my post on Derrida and dialectic below. But before I do that, I have to return to the issue of dialectic itself.
What is dialectic? I have two posts below on dialectic and language that were drafts of a presentation that I made to a class on dialectic, and, after seeing how those presentations ended up, I realize it might be better to explain the dialectic in a different way.
The reflections below were motivated by a reading of dialectic that Heidegger makes in "Hegel and the Greeks:" dialectic is the process whereby thought goes through the holding-together and gathering that takes place in language, (in Greek, dia-legein) and comes to appearance that way (so that the whole is, in Greek, dia-leges-thai).
But Heidegger offers a seemingly conflicting reading of dialectic in his early course on the Phenomenology of Spirit: there, dialectic is described as the moving between the speculative and propositional sentence. It is this latter explanation that was a bit clearer to my class, so I'll explain it that way. Hopefully, though, afterwards you can see perhaps how these two explanations are not conflicting. And hopefully we will be led to a position where we can explain a "Derridian dialectic" in a later post.
So, again, what is dialectic? It seems easy to characterize at first, but after a while, you can see that no one is really clear about what it is. Gadamer makes this clear in his book on dialectic (Hegel's Dialectic: Five Hermeneutical Studies--I recommend it). Dialectic for Hegel is not just a mode of allowing thoughts to address their contradictions, like in ancient or medieval philosophy (in saying it is "not just" these, of course I am not indicating that something of the spirit of Hegel is not in them and vice versa.) Nor is it the mere play of falsity and appearance that Kant makes it out to be in his Critique of Pure Reason, though this influences heavily the sense of "phenomenology" that we find in the Phenomenology of Spirit. Hegel's sense of dialectic is more restricted. And yet, because of this restriction, it is also the most vague: divorcing himself from the tradition of dialectic to specify a really precise concept of what it does ends up making it hard to specify without going through the entire Hegelian philosophy. In fact, this is its point: it is the Hegelian philosophy insofar as this philosophy is the interrogation of negativity and its result in spirit. One cannot extract dialectic from the interrogation of which it is a constitutive movement.
But if we understand this, we can perhaps get a little more specific as to what it is, making reference to Hegel but also trying to wrest dialectic from out of Hegel. Let's begin: dialectic is not a force or power, but a result of a force or power--specifically, "the tremendous labor of the negative." That said, dialectic as a result is always being again taken up by this negative labor, so that it can never be said to merely be the sheer content and residue that this negativity deals with. That said, dialectic cannot be a form or method that experience or spirit through the labor of the negative gets processed through--Kojeve is good in showing you that it is not the form of the labor of the negative.
So, dialectic seems to merely be what we sait it was: a "constitutive movement" of a movement (of negativity and spirit) that is larger than it. This gets us nowhere. Or does it?
Understanding dialectic as a result that is not a result, that is, not a content nor a form, allows us to account for three binaries that the dialectic itself introduces in the texts of Hegel:
Immediacy/mediation
Indeterminate/determinate
Universal/particular
The first deals with how dialectic is a result or not, the second with how it is a content or not, the third with how it is a form or not.