This chapter analyses thruthfulness and opposition to lying in saint Augustine as an element for individual and social peace building. At the same time, it addresses a dialogue between contemporary authors notably including Jacques Derrida and Hannah Arendt. The authors analyze lying as the absence of truth and as a "modern rewriting of history". In De mandacio (395) and in Contra mendacium (421), for example Augustine analyses the problem of lying as the misrepresentation of thought expressed through words or other signs with the intention of deceiving. Even in situations of conflict or stress, Augustine states, one must avoid the temptation to lie and in so doing cause harm to others. Augustine thus shows the present and meaning of the "disposition of truth" as the corner stone of individual peace as well as of concord and peace among the nations.