The observer must be distinct…that is, autonomous and not subject to–and rationally understood and defined as such–that which he observes (i.e. processes and objects). To reject and deny this necessary fact, and to launch into a philosophy (an explication of axiomatic Truth with respect to existence) based upon the objects and the processes which “govern” them, and this absent a rationally consistent definition of “observer” which does not subordinate him in the metaphysics sense (meaning he has moral and intellectual autonomy) to these objects and the processes which “govern them”, is the apogee of laziness, pseudo-intellectualism, and irrational, hypocritical, and self-nullifying mysticism. And worse yet, this will and must wreck the very thing–the only thing–which guarantees morality and therefore life and liberty: moral and intellectual awareness via absolute agency referenced to the individual (metaphysically singular–one’s “oneness”, you might say). And agency implies an agent, and by “agent”, I mean: the Self. That is, he who observes and, more importantly, conceptualizes what he observes in order that he may cognitively (which means, practically speaking, intellectually and morally) organize his environment to the promotion and perpetuation of the Self–himSelf and Other Selves.
And what is the Self?
The Self is the conceptualization of, again, one’s “oneness”. The Self is he who is inherently Able to define life–“life” being the practical manifestation of one’s will and choice via his ability to conceptualize his existence within a distinct environment–by referencing it to his own moral and intellectual agency. Further, by this ability to define a moral and intellectual reference for life–for existence–which is himSelf, distinct and autonomous from the objects and processes he observes (from the environment, that is), he may recognize both its truth and goodness, and therefore quite naturally carry a desire to possess it. For he knows that HE is True and Good. And this Truth and Goodness are axiomatic and irreducible; not subject to the objects and processes he observes and conceptualizes, a subjection in the metaphysical sense which would wreck any distinction between himSelf and his environment, thus nullifying the only rational reference for existence at all, which renders moot his ability to conceptualize, which nullifies his ideas, which destroys morality and truth.
unreformingtheology 
Its interesting I started reading Descartes recently due to silly debates with those Buddhists who say there is no self. And I noticed that your basic philosophy of “the self is the epistemological primary” is in there, expressed in way more words, and he nonetheless sometimes offers premises contrary to it, but its still there.
From “THE PRINCIPLES OF PHILOSOPHY” Part I:
“VII. That we cannot doubt of our existence while we doubt, and that this is the first knowledge we acquire when we philosophize in order.
While we thus reject all of which we can entertain the smallest doubt, and even imagine that it is false, we easily indeed suppose that there is neither God, nor sky, nor bodies, and that we ourselves even have neither hands nor feet, nor, finally, a body; but we cannot in the same way suppose that we are not while we doubt of the truth of these things; for there is a repugnance in conceiving that what thinks does not exist at the very time when it thinks. Accordingly, the knowledge, I THINK, THEREFORE I AM, is the first and most certain that occurs to one who philosophizes orderly.”
And from the Meditations, Meditation III:
“2. And in the little I have said I think I have summed up all that I really know, or at least all that up to this time I was aware I knew. Now, as I am endeavoring to extend my knowledge more widely, I will use circumspection, and consider with care whether I can still discover in myself anything further which I have not yet hitherto observed. I am certain that I am a thinking thing; but do I not therefore likewise know what is required to render me certain of a truth ? In this first knowledge, doubtless, there is nothing that gives me assurance of its truth except the clear and distinct perception of what I affirm, which would not indeed be sufficient to give me the assurance that what I say is true, if it could ever happen that anything I thus clearly and distinctly perceived should prove false; and accordingly it seems to me that I may now take as a general rule, that all that is very clearly and distinctly apprehended (conceived) is true.”
Ergo, something is true because I distinctly perceive it to be so, or “the self is the epistemological primary.”
Yes, and I think generally speaking he is quite right. And though a lot of people accuse Descarte (or, “I think therefore I am”) as avering mere solipsism, the second half of your excerpt shows this not to be the case.
He’s basically saying that the fact that he thinks implies that he can know the difference between what is true and what is false. Which is rationally consistent.