Atum

Atum is the self-created creator-god of Heliopolis, the first being, who arose of his own power from the primordial waters of Nun upon the first mound of dry land. Complete and self-sufficient — his name suggests both 'the All' and 'the not-yet-complete' — he brought the world into being out of himself, generating the first divine pair, Shu (air) and Tefnut (moisture), and so beginning the Ennead.

As the One from whom the many proceed — the source that needs nothing prior to itself — Atum struck the later Platonists and Hermetists as kin to their own first principle, the One beyond all things. At evening he was the aged form of the sun Ra, sinking back toward the waters from which all being came and to which it returns.