Dio's Rome : An Historical Narrative Originally Composed in Greek During the Reigns of Septimius Severus, Geta and Caracalla, Macrinius, Elagabalus and Alexander Severus, Volume II (Illustrated‪)‬

Cassius Dio Cocceianus, Roman senator and prætor, when about forty years of age delivered himself of a pamphlet describing the dreams and omens that had led the general Septimius Severus to hope for the imperial office which he actually secured. One evening there came to the author a note of thanks from the prince; and the temporary satisfaction of the recipient was continued in his dreams, wherein his guiding angel seemed to urge him to write a detailed account of the reign of the unworthy Commodus (Book Seventy-two), just ended. Once again did Dio glow beneath the imperial felicitations and those of the public.