A more comprehensive text , presumed to describe the life of Nerva in closer detail , is the Histories , by the contemporary historian Tacitus . The Histories is an account of the history of Rome covering three decades from the suicide of emperor Nero in 69 until the death of Domitian in 96 . Unfortunately , a substantial part of the work has been lost , with only the first five books covering the Year of the Four Emperors remaining . In the introduction to his biography of Gnaeus Julius Agricola however , Tacitus speaks highly of Nerva , describing his reign as " the dawn of a most happy age , [ when ] Nerva Caesar blended things once irreconcilable , sovereignty and freedom " .