[. . .] by itself, unity itself is not a primordial and essential determination of the being of beings. However, the inceptual thinkers necessarily come upon this unity, because the truth [Wahrheit] of being must remain concealed to them and to their inception [Anfang] and because, in order to grasp being at all, presencing must be maintained as the first and nearest feature of the emergence [Aufgehens] of being; hence hen [one], but always and immediately in terms of the many as things that emerge, go forth (become), and as things that recede, pass by (abiding-forth [Her-wesen] and ab-sencing [Ab-wesen] within presence [Anwesenheit] itself: Anaximander, Heraclitus, Parmenides).
In terms of the other inception, this unshaken and neverquestioned determination of being (unity) can and must, nevertheless, become questionable; and then unity points back to “time” (the unfathomable time of time-space). But then it also becomes clear that with the priority of presence (the present [Gegenwart]), wherein unity is grounded, something has been decided, namely, that this which is most self-evident [sc. presence] harbors the strangest decision [Entscheidung], that this decisional character belongs to the abidance [Wesung] of beyng [Seyns] and indicates the uniqueness, in each instance [jeweilige Einzigkeit], and the most primordial historicity [Geschichtlichkeit] of beyng itself. (GA 65, 459–60/CPFE, 323–24/CPOE, 362; tr. mod.)
Let us elaborate. The experience of the unity of being1 dominates the first inception of Western philosophical thinking, finding an outstanding expression in the Poem of Parmenides. Unity determines the implicit limits set out in this inception and orients the subsequent metaphysical tradition that moves within these limits. From Plato to Hegel, philosophical logic and dialectic have constantly attempted to refer all individual concepts, notions, or meanings back to one absolute concept or point of reference. As we saw in Chapter 1, the Platonic Idea is the common (koinon) element of identity and permanence in the many particulars, the “one over many,” the universal concept that unifies individual instances; accordingly, in the Republic, the fundamental unity of being1 as such is discovered in the mutual community (koinōnia) of the Ideas or concepts, attainable through a dialectical process.13 This dialectical quest of metaphysics is the search for a unifying unity, for the unity of the many—i.e., a quest for unity that sets out from the many things that are, the quest for being1 as a universal feature common to all beings as its instances.