In this article I study the transition from paganism to Christianity by focusing on the ritual of incubation (enkoimisis). In this rite people sleep in the precinct of a church or a temple in hopes of seeing healing dreams involving gods or saints. Many scholars point to incubation as a prime example of Greek cultural continuity, but if one looks more closely, one sees substantial differences between ancient Greek and Christian suppositions about incubation. The two religions did not consider their practices to be compatible. The dreams of Proclus and the miracles of Cosmas and Damian reveal opposed versions of incubation. Furthermore, the incubation dreams themselves reveal different accounts of the course of history and may be considered as ‘ritual historicizations’.