"On Truth and Lie in an Extra-Moral Sense") is an (initially) unpublished work of Friedrich Nietzsche written in 1873 one year after The Birth of Tragedy. It deals largely with epistemological questions of truth and language including the formation of concepts. Every word immediately becomes a concept inasmuch as it is not intended to serve as a reminder of the unique and wholly individualized original experience to which it owes its birth but must at the same time fit innumerable more or less similar cases—which means strictly speaking never equal—in other words a lot of unequal cases. Every concept originates through our equating what is unequal. According to Paul F. Glenn Nietzsche is arguing that "concepts are metaphors which do not correspond to reality." Although all concepts are human inventions (created by common agreement to facilitate ease of communication) human beings forget this fact after inventing them and come to believe that they are "true" and do correspond to reality. Thus Nietzsche argues that "truth" is actually: A mobile army of metaphors metonyms and anthropomorphisms—in short a sum of human relations which have been enhanced transposed and embellished poetically and rhetorically and which after long use seem firm canonical and obligatory to a people: truths are illusions about which one has forgotten that this is what they are; metaphors which are worn out and without sensuous power; coins which have lost their pictures and now matter only as metal no longer as coins. These ideas about truth and its relation to human language have been particularly influential among postmodern theorists and "On Truth and Lies in a Nonmoral Sense" is one of the works most responsible for Nietzsche's reputation (albeit a contentious one) as "the godfather of postmodernism."
