Self as Man's Primary Opposition

I found it helpful to think of Heidegger's work in terms of Kant's critique of pure reason because of the idea of our a priori principles which provides the framework or at least direction of teh inquiry. The inquiry makes sense to me as a "synthesis" of the questions and the questioner, more specifically, the questions shaped by the natuer of the questions. While certain aspects of man shape the questions such as his finitude, the limits of his language, etc. it is also interesting that he himself, as a material creature, is one of the main inhibitors of pure reason (his orientaton). I would like to think about this more, and wonder if others agree that man himself stands in oposition to his own knowing.
I also especially noted the importance of Richardson's point that man is more than just reason and therefore Heidegger investigates man in his totality. He says the inquiry, "must explain the very ontological structure of man which is the source of the propensity to pose the first three questions, and still more to pose the fourth" (31). Thankfully we have ability for fundamentl ontology which gives us the question "what is man?" to shape the quetions of what he can know, what he must do and what he may hope. It is exciting to think that we have been given principles a priori and a "natural propensity" which spurs us towards seeking our origins and transcendence.