I just "discovered" a text which is very well-known to Egyptologists and students of Ancient Egypt. Miriam Lichtheim published it as "The Memphite Theology" in vol. I of her monumental anthology, Ancient Egyptian Literature. The text we have comes from a badly damaged stone carved in the 25th Dynasty (ca.710 BC) but the inscription itself testifies that it is copy of a much older text. In the early 20th century the original text was believed to be from the Old Kingdom (2650-2135 BC), but currently there seems to be a consensus that it can't be older than the 19th Dynasty (ca.1305 BC). (My own guess for this newer dating is the presumed influence Akhenaten's monotheistic "heresy" on Egyptian polytheism, but see Hoffmeier for an argument that Akhenaten was not as theologically innovative as many believe.)
There is a polemical or perhaps merely apologetic backdrop to the text, which is that the god Ptah, whose cult was based in Memphis, is supreme over all other gods, even Atum, who was worshipped as the supreme God at Heliopolis. In the Heliopolitan theology, Atum creates the other gods, and transitively everything else, by his hands and his semen. In the Memphite theology, Atum himself is a creation of Ptah, and Ptah creates gods and the world through his heart and his tongue. Note that Egyptians believed the heart to be the physical organ most associated with thought. This means that the Memphite theology teaches that the supreme god Ptah creates things other than himself by first thinking of them with his heart and then speaking them with his tongue.
The text is obscure but oddly beautiful. Here are a few selections:
"There took shape in the heart, there took shape on the tongue the form of Atum. For the very great one is Ptah, who gave life to all the gods [...] through his heart and through his tongue, in which Horus had taken shape as Ptah, in which Thoth had taken shape as Ptah [...] Thus heart and tongue rue over all the limbs in accordance with the teaching that it [referent of "it" ambiguous: either heart or Ptah] is in every body and it [again, referent of "it" ambiguous: either tongue or Ptah] is in every mouth of all gods, all men, all cattle, all creeping things, whatever lives [... Ptah] gave birth to the gods, and from [him] every thing came forth, foods, provisions, divine offerings, all good things. Thus it is recognized and understood that he is the mightiest of the gods."
There is so much to unpack here.
Sometimes it seems to me that polytheism was just an extravagant way of talking about the many manifold power of the one simple God.