But clearly they knew nothing about it. The same holds for Tacitus. In his history of the early Empire he discusses at some length the dissolute life of the younger Agrippina, who was Caligula’s sister and the wife of the later emperor Claudius. He even considers her capable of having attempted incest with her own son, the emperor Nero. Clearly he would have mentioned any incest between Agrippina and her brother, which would have suited his account, but no such allegation was known to him. Thus the story was invented at some point after Caligula’s death.

A further example: A broadly based conspiracy against Caligula took place midway through the year 39, in which many members of the Roman aristocracy participated, including an important military commander in Germania, the emperor’s sisters, his closest confidant among the senators, and the sitting consuls. It was a highly dramatic occurrence, which threatened the emperor’s life and fundamentally altered his behavior toward his fellow members of the senatorial order. Curiously, the early sources are completely silent on the matter. Suetonius does not devote a single word to the conspiracy itself; he describes only the emperor’s apparently confused reactions to it. Yet two casual references to it in his biographies of the emperors Claudius and Vespasian reveal that the events, which are also documented in inscriptions, were well known to him.

Many more examples could easily be given, as will become apparent later. They point to the following conclusion: The accounts of Caligula surviving from antiquity pursue the clearly recognizable goal of depicting the emperor as an irrational monster. They provide demonstrably false information to support this picture of him and omit information that could contradict it. They present the emperor’s actions out of context, so that their original significance is either completely obscured or can be grasped only with great difficulty. The authors offer assessments of his behavior that often contradict other information contained in their very own accounts.