The Greek word aletheia is typically translated as "truth". Once this translation is in place, interpretations of aleetheia trade on the meanings primarily associated with "truth". The traditionally dominant meaning in this regard is correctness (the correctness of a thought or assertion) and, in fact, as early as Homer , a cognate of correctness, homoioesis, served as a synonym for aleetheia. Thus the correctness (orthotes ) of a thought or assertion tends to be understood in terms of its agreement or correspondence (homoioesis) with a state of affairs. Nevertheless, Heidegger takes exception to the interpretation of aleetheia as correctness or correspondence alone, regarding it as a derivative notion of truth. This sort of interpretation overlooks the fact that aleetheia has a much richer significance that notions of correctness presuppose. Aleetheia in that more basic sense signifies the "unhiddenness" (Unver-borgenheit) of what is asserted. For example, "The tree is sprouting" is true, that is, correct, only if the tree shows sprouts. Since what is hidden is hidden from someone, truth as the unhiddenness of "things" also entails their actual or potential presence to someone, someone with an understanding of them. The unhiddenness signified by aleetheia is accordingly irreducible to either subjects or objects. Not surprisingly, so taken were certain Greek thinkers with this sheer manifestness or presence of things that they identified it as a principal way of saying of something that it exists.
While a remarkable achievement, the appreciation of truth as unhiddenness is, Heidegger insists, far from the end of the story. For, as its privative nature suggests, "un-hiddenness" (a-letheia) supposes a hiddenness. That hiddenness is not traceable simply to either the obstruction of some entities by others or the shortsightedness of some observers. Nor is it merely the absence in the past out of which the presence of what is present emerges (like the tree before and after sprouting). Also hidden is what it means for each respective entity as well as entities as a whole to be at all - not least when being is equated with the manifestness or presence of things. Heidegger accordingly argues that the essence of truth is neither the correctness of assertions nor the unhid-denness of beings, but the truth of beyng, that is, the interplay of that hiddenness and unhiddenness (or, equivalently, absencing and presenc-ing, the strife between earth and world). Truth in this most fundamental sense - the truth of beyng - is the hidden "openness" in the midst of beings that grounds their unhiddenness and, thereby, the correctness of assertions and thoughts about them (GA65 : 342-51, 357).
Although Heidegger investigates truth as aletheia throughout his career, the investigations typically move through the three steps just noted: the correctness of thoughts and assertions, the unhiddenness of beings and the clearing for beyng’s self-concealment. He investigates these three conceptions with the understanding that, historically, truth in some sense defines human existence and human beings define themselves by the way they conceive truth. He accordingly emphasizes the enormity of the human transformation at the beginning of Western thinking, initiated by the Greek understanding of aletheia as the unhiddenness of beings. He also projects the need for a new beginning, a transformation that corresponds to the "truth of beyng", the clearing presupposed by truth as aletheia (unhiddenness). This chapter traces the general steps in Heidegger’s investigation with an eye to exposing the human transformations that, in his eyes, the interpretations of truth as aletheia in the first beginning and in a new beginning respectively entail.