From very early times down to the late periods, the Ancient Egyptians describing the firmament distinguished the “southern sky” and the “northern sky” in their texts as well as in their iconography. Representations of the sky that appear on ceilings or coffin lids permit to identify the main stars in the sky called “southern” as those that move along the ecliptic comprising, in essence, the decanal stars that mark the daily and annual course of the sun. The northern sky, on the other hand, is the domain of the boreal constellations that are visible throughout the year, which is why the Egyptians called them “Those who do not know destruction”.The “spatial” opposition is accompanied by a “mythological” one: the constellations of the northern sky are tied to the notion of immortality because they can never be seen to vanish into the Duat. Inversely, the constellations situated further to the south, with Sirius and Orion as prototypes, which are absent from the sky during a certain lapse of time in the year, are compared to the living: they “live” while they sparkle in the night firmament and “die” during their invisibility, which is perceived as a passage in the Duat. These observations explain a great variety of mythological allusions issuing from the Pyramid Texts.