A person carries a ka, the vital force needing offerings after death, and a ba, the mobile aspect of self that can leave the tomb and move between the dead and the living.

Egyptian religious texts never describe a single soul leaving the body at death the way later traditions do. Instead a person was understood as a bundle of related but distinct elements, each with its own name, its own iconography and its own fate. Alongside the physical body itself, texts speak of the ren, a person's true name, whose preservation on monuments and in speech kept that person's existence intact, the ib, the heart, seen as the seat of intelligence, memory and moral judgment and famously weighed against the feather of Maat at judgment, and the sheut, the shadow, another inseparable extension of the self. The ka and the ba sat at the center of this whole system. The ka was born with the person, often depicted in art as their exact double, standing just behind or beside them, and represented the vital force or life energy that made the difference between a living body and a corpse.

Where the ka was static and needed to be fed in place, the ba was mobile. It was not present during life in the same explicit way the ka was, becoming the personality's active vehicle only after death, free to leave the tomb, cross the horizon and travel with the sun god by day before returning to the body at night. Egyptologist Jan Assmann has argued that this multiplicity was not confusion but a deliberate theological solution: death threatened to destroy the coherent person, and distributing that person's continued existence across several linked but independently sustained elements gave Egyptian funerary religion several separate points at which restoration and survival could be secured, rather than staking everything on one fragile, singular soul.

Belief in the ka shaped tomb architecture directly. A false door, a carved panel resembling a doorway that opened onto no real passage, was built into private tombs as the point at which the ka could pass between its statue or burial place and the world of the living to receive offerings, whether real food brought by family and mortuary priests or, once that supply inevitably lapsed, the painted and relief-carved food depicted on the tomb walls and the offering formula recited or inscribed there, already living as its own entry on this religion's page as the practice Hetep Di Nesu. Wealthier tombs also included one or more ka statues, physical backups intended to house the ka permanently if the mummified body itself were ever destroyed, since the ka's survival, not the corpse's preservation alone, was what mattered.

The ba received different treatment because its defining feature was movement rather than residence. Coffins and papyri from the New Kingdom onward regularly show the ba as a small bird with a human head hovering near or above the mummy, and funerary literature such as the Book of the Dead includes specific spells, most notably Spell 89, aimed at securing the ba's reunion with the body each night, since a ba permanently separated from its corpse, or a corpse that decayed past recognition, threatened the whole afterlife project. The Pyramid Texts, centuries older still, already show royal funerary religion working through comparable anxieties for the king's own ka and ba, evidence that this composite picture of the self was not a late elaboration but close to the foundation of Egyptian funerary belief from its earliest textual attestation.