This book analyses late antique historiography and epideictic texts, focusing on how divine knowledge of imperial futures safeguarded the legitimacy of Roman emperors. It begins with Constantine and his tetrarchic colleagues (A), before moving to Constantius II and Julian (B), then Valens (C), and ending with Theodosius and Honorius (D).The impact of future knowledge in these texts could be felt both in the present circumstances of their composition and in perpetuity, as visions of the future reflect either the confidence or boastful arrogance of history’s protagonists, their divine inspiration or doom, and ultimately, their place in imperial memory.