Although Nun is chiefly known as an abstract precondition of the universe rather than an actor within it, one striking New Kingdom composition, generally called the Book of the Heavenly Cow, gives him a speaking role and treats him as the eldest and most authoritative of the gods, one addressed in council rather than merely present at the world's beginning.
In the story, the sun god Ra, grown old, learns that humankind has begun plotting rebellion against him, and he summons the great gods, including Nun, Shu and Geb, in secret council to decide what should be done, deliberately consulting Nun first as the primordial father of the gods whose judgment carries special weight precisely because he predates creation itself.
Nun advises Ra to send his fierce Eye, the goddess who becomes the lioness Sekhmet, down to punish the rebellious humans, setting in motion the myth's famous near-annihilation of the human race and the beer trick by which Ra finally restrains the goddess's bloodlust and spares what remains of humanity. The episode is theologically significant precisely because it interrupts Nun's usual passivity: for one myth, the shapeless waters that exist before and beneath creation are given a voice and asked for guidance, a reminder that the Egyptians could treat their most abstract cosmological principles as personal enough to advise, when the narrative required it, even a principle as vast and formless as the primeval ocean itself.