This paper examines the series of dreams in the Vita Basilii, narrated by the text of the Continuation of Theophanes and illustrated by the miniatures of the Escorial Skylitzes. It focusses on the political use and appropriation of prophetic dreams for justifying the irregular rise to the imperial throne of Basil I and the subsequent change of the ruling dynasty of Byzantium. The dreams legitimise this historical process, offering divine approval to Basil and his somewhat unconventional methods. A wide range of dream types is employed, with diverse legitimising functions and specific uses. Their illustrations present us with a unique specimen of depictions of the ‘political’ historiographical dream. In both their written and painted versions, these dreams clearly serve the holders of political power, but also -through their implied divine origin- the servants of their alleged sender, strengthening the ties of religious authority to political power.