"The Lives of the Twelve Caesars, Volume 10: Vespasian" by Suetonius is a biography written in 121 CE. This volume is part of Suetonius's larger work chronicling Julius Caesar and the first eleven Roman emperors. Written while serving as secretary to Emperor Hadrian, Suetonius offers an intimate portrait of Vespasian, drawing on personal details and political insights. Though criticized for relying on gossip and sensationalism, the work remains a crucial primary source, especially valuable since other historical accounts have been lost to time. (This is an automatically generated summary.)