Iusaaset (//; "the great one who comes forth") or Iusaas (//) is a primordial goddess in Ancient Egyptian religion. In Egyptian texts, she is described as "the grandmother of all of the deities". This allusion is without any reference to a grandfather, so there might have been a very early, but now lost, myth with parthenogenesis as the means of the birth of the deities from the region where her cult arose near the delta of the Nile. There are many alternative spellings of her name, including Iusaaset, Iusaas, Juesaes, Ausaas, and Jusas, as well as in Greek Saosis //.
In Ancient Egyptian art, Iusaaset appears as a woman wearing the vulture crown of Mut, another mother goddess, topped with the solar disk between cow horns, the headdress of Hathor. She carries an ankh in one hand and a was sceptre in the other, and sometimes her crown bore a uraeus (Egyptian cobra), representing the goddess Wadjet. The Egyptian vulture that made up her crown symbolised the goddess Nekhbet, the other one of the Two Ladies protecting Egypt, alongside Wadjet. The Egyptian vulture was also thought to reproduce though parthenogenesis, which might be the basis for a similar view about the motherhood of Iusaaset. The vultures were also considered extremely good mothers, protecting their chicks at any cost, so it is not surprising that mother goddesses like Nekhbet, Iusaaset and Mut were portrayed as or with them.
Because of Iusaaset's link to the vulture and uraeus, it can be assumed that she links together both upper and lower Egypt, much like the goddess Mut, with whom she is closely associated.
Although her origins are unclear, Iusaaset seems to be attested quite early in the Egyptian pantheon, being associated with creation in general and the creation of the deities in particular. Many myths relate that she was seen as the mother of the first deities and the grandmother of the following deities, having watched over the birth of the ones that were her grandchildren. She remained a primary deity in the pantheon throughout all eras of the culture, even through the Persian, Hykso, Greek, and Roman occupations, and regardless of changes in the specific myths.
Iusaaset was associated with the acacia tree,[unreliable source?] considered the tree of life by the Egyptians. The oldest known acacia tree was situated just north of Heliopolis, which therefore became identified as the birthplace of the deities. Iusaaset was said to own this tree, just as Osiris owned the sacred willow. The acacia tree was renowned for its strength, hardiness, medical properties, and edibility. Many useful applications gave it a central importance in Egyptian culture.
One belief, particularly prominent in Heliopolis, held that Iusaaset and Atum were the parents of Shu and Tefnut, the first deities. In this myth she was often described as the shadow, sister, or wife of Atum. In later periods, other goddesses also became associated with Atum, and one variant even relates that he gave birth to the deities himself.
During the Old Kingdom, the Egyptians believed that Atum lifted the dead pharaoh's soul from the tomb to the starry heavens, associating him with the heavens, and in particular the greatest heavenly object in Egyptian thought: the Sun. By the time of the New Kingdom, the myth of Atum had merged with that of Ra, who was likewise described as a creator deity and a solar deity as his cult arose. Their two identities were joined together to form Atum-Ra. After they were combined, Ra came to be seen as the sun at midday and Atum as the sun when it sets in the west (depicted as an old man leaning on his staff), while Khepri was seen as the sun when it was rising.