Selected Discourses from the Pitāputrasamāgama Sūtra

The Buddha said: "O King, it is indeed so. Foolish ordinary beings, lacking in learning and wisdom, develop affection and delight toward agreeable contacts, giving rise to mental defilement and attachment. They create such karmas: three kinds of bodily karmas, four kinds of verbal karmas, and three kinds of mental karmas. Having created those karmas, they vanish instantaneously moment after moment. Once these karmas cease, they do not abide in the east, south, west, north, the four intermediate directions, above, below, or in between. Yet at the moment of death, one sees past actions appear in the mind, just as a person, upon awakening, recalls the events of a dream. When the final consciousness ceases, one's own karma manifests."

Foolishness is ignorance—understanding nothing. Not knowing what the five aggregates are, not knowing the emptiness and falsity of the five aggregates, not knowing the illusory nature of all dharmas, not knowing that this false self is a composite, not knowing how to dismantle it, not knowing how to escape the six paths of rebirth, not knowing how to attain the fruition of a bodhisattva, not knowing how to realize one's original face—the inherently pure mind—and even not knowing how to attain Buddhahood. All this is called foolishness and ignorance.

When the lifespan of a presently living being ends, the next phase of existence will begin elsewhere, taking rebirth in whichever realm corresponds to their habitual tendencies and karmic force. The change in time, place, and physical form is called 'differentiation'. After death, beings typically undergo complete transformation in body, time, identity, location, and living space. Hungry ghosts inhabit the space of hungry ghosts, asuras the space of asuras, hell beings the space of hell, and celestial beings the space of heavens. Animals coexist with humans on the earth's surface, yet their living environment still differs. When the living environment changes, transforming into another life form and becoming a different kind of living being, this is called 'differentiated birth'.