Here is what the myth of the "creation" of the world has to say about this:
In the beginning God began to create himself out of the "Nun" of Hidden essence and his name was Atum. When he had appeared, Atum created everything that arose from his essence and he was within his creation, as in his body. Atum was the first, the father and creator of all other gods, the maker of all that exists, [he was] single and uncreated. Then Atum set about creating the other gods. First he exhaled [the first energy body] Shu, then [the next] his sister Tefnut. Then there appeared [the remaining energy bodies] Nut, Geb, Osiris, Isis, Seth and Neftis...
Nun in Ancient Egyptian means Primaeval waters (original energy).
In Ancient Egyptian Atum means both "Everything" and "Nothing".