  Heidegger’s description of this essential conflict between earth and world should be understood as his attempt to elaborate phenomenologically his enduring ontological understanding of truth as the inherently agonistic manifestation of a-lêtheia, that is, “truth” conceived ontologically as historically-variable “un-concealment” or “dis-closure.” It is, we could say, the hyphen in a-lêtheia—the joining together, literally “under one” (hypo + hen), of revealing and concealing—that Heidegger develops as the essential strife between world and  earth.[65] With world and earth, in other words, Heidegger seeks to name and so render visible the quietly conflictual structure at the heart of intelligibility, the unified opposition that allows “being” to be “dis-closed” in time. Since Being and Time at least, Heidegger had insisted on the “equiprimordiality” or “co-originality” (Gleichursprünglichkeit) of “truth” and “untruth” (BT 265/SZ 222), building on Husserl’s phenomenological axiom that the emergence of one thing or aspect of a thing into intelligibility requires the concealing of another. (Taken to its extreme, this axiom allows Heidegger to suggest that the totality of what-is stands in the place of and so conceals the “nothing” from which it  emerges.)[66] For Heidegger, the fact that there can be no revealing without concealing (and vice versa) is a necessary feature not just of perception or cognition but of intelligibility in  general.[67] 