Although the historian Herodian is generally considered unreliable and his Roman History contains several notable errors, his written description of the apotheosis of an emperor may be considered reliable, particularly as the ritual described is in essence a standard Roman funeral of antiquity writ large.

Ancient Romans practiced the rite of ancestor-worship; every day they would pray to their ancestors as well as to the general household spirits. The (early) Roman view of the afterlife was similar to that of the ancient Greeks, one in which the deceased was merely a spirit that was, pun intended, a mere shade of its' former self. This is why family was so important to Romans, and why a Roman without heirs would do his best to adopt one. A Roman survived after his death only as long as he was remembered and the proper rites carried out.

It is with this in mind that the idea of the apotheosis of a deceased emperor must be considered. An ordinary Roman paterfamilias, upon his death, was elevated to the status of a deity for his family; a deceased emperor, who was paterfamilias for the entire Roman People, therefore was being elevated to the status of a deity for all his 'family' - that being all the Romans.

A Roman funeral (for a citizen of sufficient status) would begin with a lying-in-state for seven days, with the body dressed in all honors the deceased had acquired in life. In the case of the deceased Emperor, it was his wax imago that was placed out for the customary week.

A funeral procession would be headed by musicians providing mournful paens; the imperial funeral was no different in this respect. Although a non-imperial roman funeral would have an actor wearing a mask of the deceased and imitating the characteristics, this was rendered unnecessary since the imago was itself already standing in for the deceased emperor. A roman funeral would also involve mimes wearing imagii of the deceased's notable ancestors; an imperial funeral involved the wearing of images of past generals and emperors. Again, this is an expansion of standard Roman funeral practices.

The deceased in normal practice was carried to his pyre on a couch carried by his close relations or by his freedmen; Emperors were carried by Senators.

Cremation on a pyre was, of course, a Roman practice of great antiquity, although it was never the exclusive practice (the Cornelii for one practiced inhumation). Throwing perfumes and other items of fair odors is almost a requirement for an open cremation of a human corpse due to the odor produced; a wax corpse does not require such things, but custom is king, and as in all things Emperors get the best.

Therefore the apotheosis of an emperor is, from a certain point of view, merely the extension of long-standing traditional Roman practice to the grandest possible scale.