In Plotinus, all things proceed from the One by emanation, without diminishing it, as light from the sun or heat from fire: first Intellect, then Soul, then the material world. The idea shaped Islamic philosophy, Kabbalah and Christian mysticism, and is paired with the return of all things to their source.
Emanation
The flowing forth of reality from a single source, as light from the sun, in Neoplatonism and related traditions.
Also: proodos, procession