The practical demands of sustaining a ka indefinitely shaped Egyptian funerary religion into something closer to an ongoing institution than a single ceremony. A wealthy family could endow agricultural land or income specifically to fund offerings at a tomb chapel, hiring ka-priests, hem-ka, whose profession was to perform the offering ritual on a schedule, sometimes for generations after the original family had died out and could no longer perform the rites themselves.
Egyptian funerary texts also supply a fallback for when the living offering economy inevitably failed, as endowments lapsed or dynasties fell: an offering formula, the hetep-di-nesu, inscribed on tomb walls and stelae, invoking the king's favour to provide the deceased with bread, beer, oxen, fowl and every good and pure thing by the recitation of the words alone, on the theory that the spoken or even merely inscribed formula carried real sustaining power independent of an actual meal being physically present. This is one of the clearer instances in Egyptian religion of language itself being treated as efficacious rather than merely descriptive.
Tomb statues of the deceased served a related function, as an alternative body the ka could inhabit should the mummy be destroyed, robbed or otherwise lost, spreading the risk of the ka's continued survival across more than one physical anchor. Taken together, the offering cult, the endowed priesthood, the recited formula and the substitute statue represent a remarkably comprehensive set of institutional responses to a single religious problem: keeping a vital force alive that, by definition, could no longer feed itself.