Before the world existed, there was only Nun, a dark and endless ocean of chaos without form, without light, and without time. No land, no sky, no gods, no men - only the infinite waters stretching in every direction. From this nothingness, Atum created himself through sheer will, rising upon a mound of earth called the benben that broke the surface of Nun like the first island in a flooded world. He stood alone upon that primordial hill at Heliopolis, the city that would become the greatest religious centre in Egypt, and looked out over the waters that still surrounded him on every side. He was the Complete One, the accomplished god who contained within himself all that would ever be, and he knew that he must create order from the chaos that pressed against his island.

Atum looked upon the empty cosmos and realised that he was alone. In the earliest tellings, he created the first divine pair from his own body, spitting forth Shu, the god of dry air and breath, and Tefnut, the goddess of moisture and order. In other versions he brought them into being through an act of self-creation, using his own hand as the female principle within himself, or mating with his own shadow upon the benben. Shu and Tefnut were the first differentiation, the first breath and the first drop of water in a universe that had known neither, and they represented the emergence of space itself amid the formless waters. But the two young gods wandered away from their father into the darkness beyond the mound, and Atum, left alone again, tore out his own eye and sent it searching for them across the wastes of Nun. The eye found the twins and brought them back, and when Atum embraced his children again, he wept tears of such joy that they fell upon the benben and became the first human beings, born from the sorrow and happiness of the creator himself.

Shu and Tefnut grew and joined together, giving birth to Geb, the god of the earth, and Nut, the goddess of the sky. Geb and Nut fell in love and clung to one another so tightly that there was no space between them for anything to live, and Atum saw that the world could not flourish while the earth and sky were locked in this eternal embrace. He commanded Shu to stand between them, and the air god raised his arms and lifted Nut high above Geb, creating the space in which the sun could sail and mortals could walk. But Atum had acted too late to prevent the union entirely, and Nut was already pregnant. She gave birth to four children: Osiris, the god of fertility and resurrection; Isis, the goddess of magic and motherhood; Set, the red-haired god of chaos and desert storms; and Nephthys, the goddess of protection and mourning. Atum looked upon these four and saw that Osiris was the wisest and fairest, and he granted him dominion over the earth, completing the Ennead of Heliopolis, the nine gods who governed the cosmos.

As the centuries passed, Atum became inseparable from Ra, the great sun god whose cult rose to dominate Egypt. The two merged into Atum-Ra, a single deity who embodied the complete journey of the sun across the sky. Ra was the morning and midday sun, the blazing disk at the height of his power, while Atum was the evening sun, the aged god who entered the western horizon and sailed through the underworld in his night-bark. In this form he was an old man leaning upon his staff, travelling through the twelve hours of darkness and battling the serpent Apep, the demon of chaos who attacked the sun boat each night, threatening to swallow the light and return the world to the darkness of Nun. Atum-Ra stood in the prow of the bark with his divine protectors, and each dawn he was reborn as Khepri, the scarab god of the rising sun, completing the eternal cycle.

In the Coffin Texts, a collection of spells carved upon the coffins of the Middle Kingdom, Atum speaks to Osiris of the end of all things. He tells the lord of the dead that after millions of years he will destroy everything he created, submerging the world beneath the formless waters of Nun once more. Only Atum and Osiris will survive, existing in that watery darkness as serpents, coiled and waiting until the moment comes to begin creation anew. This was not a threat but a promise, the natural conclusion of a cycle that began with emergence and must end with return. Pharaohs across three thousand years claimed Atum as their divine father, calling themselves the Son of Atum, and the god placed the double crown upon their heads in temple ceremonies that bound the king to the creator. The last surviving remnant of his temple at Heliopolis is an obelisk erected by Senusret I of the Twelfth Dynasty, still standing in modern Al-Matariyyah, a stone witness to the god who made himself from nothing.