This as-structure—or more precisely, the act of dealing-with as a direct having and taking, insofar as it is determined by the as-structure—determines our being unto the world and in large measure even our being unto ourselves. For its part, sense-making is possible as a basic form of our being only because our existence itself is capable of understanding. Even if one’s existence is thick and dull, that dullness is merely one mode of the understanding that necessarily belongs to every existence that is being in the world. Obviously the mode of understanding can vary widely. 
The act of making-sense or understanding is directed primarily not to individual things and to general concepts. Instead, it is alive in one’s firsthand lived world and in one’s world as a whole. In this act of sense-making, the world is opened up for existence. This disclosure is the uncovering of the current form of a being’s suitability-for, whereby it is present as a being. Whatever gets opened up this way can be held on to, even when the worldly thing in question is not itself present. That is, the opening-up of the world—which unfolds in the act of understanding or sense-making—can be possessed and preserved as meaning, i.e., as a world of understanding in which existence operates.16
* * *
In the preceding lecture hour, we delineated the structure of the “as” more precisely. It is important in analyses like this to remember the context we are working in. Briefly: Our topic is truth, specifically the truth of λόγος and more precisely yet, the question “What makes λόγος as such able to be true or false?” Aristotle’s answer is: λόγος can be true or false because it has the structure of σύνθεσις. So we asked how much λόγος has to do with σύνθεσις. Further study showed that σύνθεσις is only one structural moment of λόγος, and it is necessarily accompanied by διαίρεσις. That led to a further question: Which phenomenon possesses these two properties in a unified way?
That phenomenon is the “as,” the structure that belongs to understanding as such. Here understanding must be understood as a basic form of being of our existence. This form of being is defined as one which always already lives ahead in the source of sense-making (in
16.[Here the lecture of Tuesday, 8 December 1925, draws to a close, to be followed by the twenty-first lecture on Thursday, 10 December (Moser, p. 319). Whereas up to this point GA 21 has omitted all summaries of the previous lecture, here (GA 21, pp. 150–151 n. 6) the text provides part of the summary that Heidegger read out at the beginning of his 12 December lecture, but confines it to a long footnote. For the complete summary that Heidegger read in class and that I draw on, cf. Moser, pp. 319–324. I put the summary in its proper place at the beginning of the lecture.]
Logic : the question of truth
GA 21 p. 150