Being in Hegel's "With What Must Science Begin?" (finished)

There is confusion and a seeming contradition in perhaps the most essential passage to grasp within this crucial preliminary remark in Hegel's Science of Logic.
Hegel says the following:

[At the end of the Phenomenology of Spirit] pure knowing as concentrated into this unity [of subject and object] has sublated all reference to an other and to mediation; it is without any distinction and as thus distinctionless ceases itself to be knowledge; what is present is only simple immediacy.
Simple immediacy is itself an expression of reflection and contains a reference to its distinction from what is mediated. This simple immediacy, therefore, in its true expression is pure being. Just as pure [i.e. infinite], knowing is to mean knowing as such, quite abstractly, so too pure being is to mean nothing but being in general: being, and nothing else, without any further specification and filling. [It is with this, therefore, that the Science of Logic must begin.]
-Science of Logic, "With What Must Science Begin?," 69.

Everything revolves around grasping of the necessity of the "therefore" within this passage. This "therefore" says essentially the following in this passage: simple immediacy is pure being because simple immediacy contains a reference to its distinction from what is mediated. But this "therefore" seems to go against what it attempts to prove: it seeks tp prove the link between pure being and simple immediacy, when pure being, unlike simple immediacy, which contains a reference to its distinction from what is mediated, is defined as being, and nothing else, without any further specification and filling. In other words, something that is a reflection, that contains a determination, is linked via this "therefore" to something that supposedly must have no filling, or as Hegel says later, "cannot contain within itself any determination, any content" (70).
Let's clear this up, for in answering this question, we understand nothing less than two things: 1) how Science must begin, i.e. we understand why we must begin Science with pure being and 2) we understand why we can move past pure being to anything else, i.e. we understand that most basic of movements in the Logic from pure being to nothingness to becoming and then to determinate being, from which we can easily project other determinations. In short, understanding this means understanding how determination originates, which is nothing less than understanding how dialectic and speculative thought in general originates.
Our question reduces to the following: simple immediacy contains a determination. Pure being does not. How are the two "therefore" identical?
First we must clarify something that already sounds odd about the first term in this identity: that simple immediacy should contain a determination, should be a reflection. Immediacy is in complete contradistinction to the mediate: the mediate contains determinations while the immediate does not. In Hegel's words, if something posseses any determination, any content, this "would be a distinguishing and an interrelationship of [the] distinct moments [of the thing], and consequently a mediation" of the thing considered (70). Now, doesn't saying that "simple immediacy is itself an expression of reflection and contains a reference to its distinction from what is mediated" mean that what is distinguished from mediation, the simply immediate, is, as immediate, mediated?!
I guess if we were to superficially investigate what Hegel is getting at here we would look at what is signified by "reference" in saying that the simply immediate contains a reference to its distinction from the mediated. But the problem does not lie with the mere word "reference" or with referentiality in general. It lies in refrentiality being an expression of reflection, or, more simply put, with the determination of the immediate only through the development its immediacy as a certain type of mediation, namely, reflection. That is, it lies in the point in which the immediate transfers itself and transforms itself into the mediated. Thus, we won't get into what exactly "reflection" means for Hegel, and even less will we bother with what "reference" means, but we will specify how this point is, within the sphere of pure being that we are considering and trying to render commensurable with pure being, the already mediated immediacy inherent to the simply immediate, which is, Hegel asserts, the determination of pure being.
Let's put this in a simpler way. Simple immediacy contains a determination. Hegel will show us that the immediate can, in a special way, contain a determination. Doing show will therefore allow us to see how pure being is simple immediacy, and, at the same time, how it must be the beginning of Science, for the beginning must be in contradistinction to what is not simple and therefore contains a determination in a different way.
Now, Hegel shows us that the immediate can contain a determination, and thus a mediation, when it passes, as immediate, into its opposite. Already we can hear the inner workings of the dialectic begin to announce themselves in their essential nature: the dialectic will inhabit this process of mediation by something passing unhindered into an opposite, not by this something setting itself up against anything and then "resolving" the contradiction that it has created. The dialectic is an internal, subtle movement whereby one thing becomes identical to another at the same time that it is distinguished from it. It is never at work directly where there is a "compromise," and anyone saying so has never read Hegel. But back to the point: the immediate can contain a determination, and thus a mediation, when it passes into its opposite while remaining as itself, as immediate. How can it pass into its opposite? By making itself identical to that opposite even in its distinguishedness from it. This is obvious. But we are dealing with the immediate--and, in the case to which the immediate must apply most rigorously, pure being as what is supposed to be the simply immediate. How can something have an opposite if it is immediate purely, simply? That is the real question--and we begin to understand Hegel's use of terms like "simple" when we pose it. For anything can be opposed to anything, and immediacy in general can be just another one of these things. But the real question we are looking at is how immediacy, at its origin, can possibly become opposed to something and therefore pass into it so as to be determined (in a sense we have yet to specify). Now, immediacy can have an opposite in this original sense--i.e. when it is immediate simply--if it is already this opposite.
How can this happen? How can what is simple and immediate already be its opposite? If it is in its identity already its difference to itself. If it contains a difference within itself such that it is both its identity and, in its identity, its difference from itself. Expressed in different terms, if it is what it is not, at the very same time that it is. That is, if it is its negation. What do we mean by negation? Well, that, at its most basic level, what is simply immediate is both what it is, and what it is in its nothingness. Here is where we understand the passage regarding being in the Science of Logic. It merely reflects the structure this first necessity of showing how what is immediate and simple can be mediated. Being, Hegel asserts, is, in its innermost essence, the same as nothing, and vice versa. What this means is what we have been getting at: that something is already its opposite when it is what it is in its nothingness. In other words, we understand by this passage, which we shall refrain from explicating in detail in favor of bringing out this fundamental problem of the mediatedness of the immediate--we understand by this passage nothing other than how what is something (immediacy, for us) can be already its opposite: it can be already its opposite by being at the same time both extant and not extant, both being and nothing, both what it is and what it is not. If simple immediacy can, at its very core, be the same thing as nothingness, then it can already be its opposite. For what is immediate and simple then is at the same time as it is itself not itself. This is what we mean in saying that simple immediacy can already be its opposite by being its negation.
If simple immediacy is, at the same time as it is itself, not itself, it passes obviously into its opposite, i.e. what is not itself, both already, and as itself. While remaining itself, it becomes what is not itself. If it is immediate, and also simply immediate, it is already then what is not itself. If it is already this opposite, it has a determination. Now, this determination is not directly "mediated,"--we must be careful of attributing this to what simple immediacy is in its opposition to itself too quickly. For what the determination of the simple immediacy passing into its opposite really is, is not just what we naturally think to be the opposite of whatever term we are starting with--i.e. simple immediacy. That would be to confuse the determination with the opposition that the simple immediacy passes into. And again this is why people who say the dialectic generates its oppositions arbitrarily have never read Hegel--or at least have never read thir Hegel closely. Conceived rightly, the determination lies not in what is opposed, but in the way that the opposed was passed into. That is, it was precisely not passed into as something external to the simple immediacy. Rather, it was passed into by this immediacy developing itself, i.e. by existing as itself. The determinacy lies in how the opposite was passed into already, and not as a result of this process of passing into. This already is the determination that has been accessed by the process: it matters not what the opposite is of any immediacy, but rather that it was contained already within the immediacy as such--was only actualized where before it was latent or only potential. (We might remark that is here that Hegel most essentially reaches back to Aristotle and the original dialecticians.) In passing into its opposite, simple immediacy in this case has passed into its opposite as what it is already--this is the origin of the expression "y is the truth of x," the characteristic speculative way of talking about this behavior. What is "true" is what has a determination that is internal to what, as immediate, develops or passes into its opposite. What is false or contingent is obviously what is external to this development. Thus, saying that immediacy passes into its opposite as what it is already is saying that simple immediacy has passed into its truth.
Anyway, as these last remarks are inessential to what we are trying to show, we should summarize what we have gleaned from this process of watching simple immediateness or indeterminateness itself pass into its opposite: it has determined itself as passing into its opposite as something that already contains this opposite, already is this opposite--as something that only has passed into what it already is. This is the determination of the immediate, if we consider this immediacy simply: it should be quite clear then, that the immediate is therefore mediated, and mediated already in its immediacy: what is indeterminate has already become determined in its remaining indeterminate, simple, immediate.
It should be obvious now that what we have just described, the process of becoming the opposite of oneself while retaining that self or that identity, is what Hegel means by saying that immediacies are, within the dialectic, Aufgehoben. The term Aufheben means nothing other than what we have just described, i.e., how something can contain a determination as immediate, and thus be simple immediacy at the same time that it is mediated.
With respect to being as that with which Science must begin, clearly--as we have already remarked--describing how something can be immediate and mediated at the same time is all that is done by the section on being. As what turns into its opposite first and foremost, being must be that with which Science must begin. Nothing becomes what being turns into or is identical with, and becoming expresses the determination that constitutes the truth of being, its development as being into nothing.
But we started on this reflection to elaborate really how simple immediacy can be being in the first place if being is not determined and simple immediacy "contained a reference to a determination:" since then we've said being is a mere function of what is contained in this elaboration, and have not returned to this original point. It should be clear now that since being is what simple immediacy needs to be if it is to contain a reference to a determination, i.e. to be mediated as we have shown, through being at base what is opposed and yet identical to nothingness, being just is simple immediacy itself. Thus the "therefore" of the passage above is comprehended: we see that pure being is what simple immediacy really is at its core. Science must begin with being, then, because it is the simply immediate, and with the simply immediate because it is being--and this is because Science is nothing other than the elaboration of the necessity of determination: as what makes possible determination, being as the core of the simply immediate is the beginning of Science.
This last remark will no doubt have to remain a little fuzzy, as well as the relationship between the passage on being and the issue of simple immediacy and mediation in general, but I hope this has brought out at least how the dialectic can be conceived correctly and how fundamental a role it plays in understanding even minor statements in Hegel.