remains indefinite, indeterminable; it then coincides for the most part with what is most fleeting and most unconsidered. However, what brings into accord is not nothing, but rather a concealing of beings as a whole. Precisely because letting-be always lets beings be in a particular comportment that relates to them and thus discloses them, it conceals beings as a whole. Letting-be is intrinsically at the same time a concealing. In the ek-sistent freedom of Da-sein a concealing of beings as a whole comes to pass [ereignet sich]. Here there is concealment.a
6. UNTRUTH AS CONCEALING
 Concealment deprives ἀλήθεια of disclosure yet does not render it στέρησις (privation); rather, concealment preserves what is most proper to ἀλήθεια as its own. Considered with respect to truth as disclosedness, concealment is then un-disclosedness and accordingly the un-truth that is most proper to the essence of truth. The concealment of beings as a whole does not first show up subsequently as a consequence of the fact that knowledge of beings is always fragmentary. The concealment of beings as a whole, un-truth proper, is older than every openedness of this or that being. It is older even than letting-be itself, which in disclosing already holds concealed and comports itself toward concealing. What conserves letting-be in this relatedness to concealing? Nothing less than the concealing of what is concealed as a whole, of beings as such, i.e., the mystery; not a particular mystery regarding this or that, but rather the mystery - that, in general, mystery (the concealing of what is concealed) as such holds sway throughout the Da-sein of human beings.
In letting beings as a whole be, which discloses and at the same time conceals, it happens that concealing appears as what is first of all concealed. Insofar as it ek-sists, Da-sein conserves the first and broadest undisclosedness, un-truth proper. Τhe prοper non-essence of truth is the mystery. Here non-essence does not yet have the sense- of inferiority to essence in the sense of what is general (κοινόν, γένος), its possibilitas and the ground of its possibility. on-essence is here what in such a sense would be a pre-essential essence. But "nonessence" means at first and for the most part the deformation of that already inferior essence. Indeed, in each of these significations the non-essence remains always in its own way essential to the essence and never becomes unessential in the sense of irrelevant.  But to speak of nonessence and untruth in this manner goes very much
a First edition, 1943: Between 5 and 6, the leap into the turning (whose essence unfolds in the event of appropriation).