But self-deception is only one of many modes in which human beings move in the interlocking triple world of Being, unconcealment, and seeming.

The space, so to speak, that opens itself up in the interlocking of Being, unconcealment, and seeming, I understand as errancy. Seeming, deception, delusion, errancy stand in definite relations as regards their essences and their ways of happening, relations that have long been misinterpreted for us by psychology and epistemology, relations that we therefore in our everyday Dasein barely still experience and barely recognize with adequate perspicacity as powers.

It was necessary first to make clear how, on the grounds of the Greek interpretation of Being as φύσις, and only on these grounds, both truth in the sense of unconcealment and seeming as a definite mode of the arising self-showing belong necessarily to Being.

Being and seeming belong together, and as belonging together are constantly by one another, and in this by-one-another they also always exhibit change from one to the other and hence constant confusion, and hence the possibility of aberration and mistakes. For this reason, the chief effort of thinking at the inception of philosophy—that is, in the first opening-up of the Being of beings—had to consist in controlling the urgency of Being in seeming, in distinguishing Being from seeming. This in turn demands that truth as unconcealment be brought forward against concealment, disclosing against closing off as covering over and disguising. Inasmuch as Being has to be distinguished from something other and reinforced as φύσις, Being is distinguished from not-Being, but not-Being is also distinguished from seeming. The two distinctions do not coincide. [84|117]

Because matters stand in this way with Being, seeming, and not-Being, three paths are necessary for the humans who stand in the midst of self-opening Being and who always relate to beings in such and such a way in accord with that stance.