Differance is best approached by the via negativa: it is neither a word nor a concept, it is neither of the sensible nor of the intelligible order, neither speech nor writing, but nevertheless somehow "between" all of these. Instead of answering the question "What is differance?", Derrida first tells us what it puts into question: namely, the quest for a rightful beginning, an absolute point of departure, a principal responsibility. While we approach differance as many have approached God, it puts into question the idea of God.
Differance can be understood positively as both a deferring and a differing, a temporization and a spacing. It is the irreducibly polysemic play that designates, constitutes and produces differences. This play that takes place "before" difference is an effect of language: it is because signs represent deferred presence that we experience temporally. The play of signs in differance is the condition of the possibility of conceptuality (thus why differance is not a concept). Derrida summarizes his points as follows: "What is written as differance, then, will be the playing movement that "produces" - by means of something that is not simply an activity - these differences, these effects of difference.... Differance is the non-full, non-simple, structured and differentiating origin of differences. Thus, the name "origin" no longer suits it."
Accepting differance means coming to posit presence no longer as the absolutely central form of Being but as a determination or effect. This also means putting consciousness into question in its assured certainty of itself. Derrida cites Nietzsche and Freud as representing the primary thinkers of differance: Nietzsche's doctrine of eternal return is a myth of differance and Freud's unconscious is represented as a site of the play of differance. Derrida spends a good deal of time on Freud, noting how the difference and the similarity of the pleasure principle and the death instinct demonstrate the two sides of differance and eternal recurrence: an unceasing coming back to the same thing (pleasure) and yet at the same time a plunging into the void of absolute alterity as a result of an irreparable loss of presence (death). Differance involves an investment in which one both wins and loses, thus shattering the Hegelian idea of "return." With every recuperation, a certain radical alterity is exempt from the process of presentation that then serves in the creation of new differences that themselves do not refer back to any origin. Remaining with Freud a little longer, Derrida invokes his concept of Nachtraglichkeit, or "afterwardsness" (a translation from a psychoanalytic dictionary). In afterwardsness, the past is something that can be reconstituted based upon events of the present; it is thus not a stable origin but rewritten with every present writing.
Levinas calls the absolute alterity around which differance plays the Other. Since differance gravitates around this Other that is outside the difference between Being and beings, it is not. It governs nothing, reigns over nothing, and nowhere exercises any authority.
Derrida ends with an analysis of Heidegger’s Anaximander Fragment, where he says “Since Being has never had a ‘meaning,’ has never been thought or said as such, except by dissimulating itself in beings, then differance, in a certain and very strange way, (is) “older” than the ontological difference or than the truth of Being.” differance, which has no unique name or proper word, is at the margin of philosophy, which is the search for the unique name and proper word. It is not the ineffable Being of negative theology but an unnameable that makes possible nominal effects. There is no unique name (which is why we get trace, supplement, archi, etc.), and we must affirm this play as Nietzsche did.