that the spell aims to accomplish. In one spell, Isis creates a snake that bites Ra, who is older and greater than she is, and makes him ill with its venom. She offers to cure Ra if he will tell her his true, secret name—a piece of knowledge that carries with it incomparable power. After much coercion, Ra tells her his name, which she passes on to Horus, bolstering his royal authority. The story may be meant as an origin story to explain why Isis's magical ability surpasses that of other deities, but because she uses magic to subdue Ra, the story seems to treat her as having such abilities even before learning his name. Sky goddess Many of the roles Isis acquired gave her an important position in the sky. Passages in the Pyramid Texts connect Isis closely with Sopdet, the goddess representing the star Sirius, whose relationship with her husband Sah—the constellation Orion—and their son Sopdu parallels Isis's relations with Osiris and Horus. Sirius's heliacal rising, just before the start of the Nile flood, gave Sopdet a close connection with the flood and the resulting growth of plants. Partly because of her relationship with Sopdet, Isis was also linked with the flood, which was sometimes equated with the tears she shed for Osiris. By Ptolemaic times she was connected with rain, which Egyptian texts call a "Nile in the sky"; with the sun as the protector of Ra's barque; and with the moon, possibly because she was linked with the Greek lunar goddess Artemis by a shared connection with an Egyptian fertility goddess, Bastet. In hymns inscribed at Philae she is called the "Lady of Heaven" whose dominion over the sky parallels Osiris's rule over the Duat and Horus's kingship on earth. Universal goddess In Ptolemaic times Isis's sphere of influence could include the entire cosmos. As the deity that protected Egypt and endorsed its king, she had power over all nations, and as the provider of rain, she enlivened the natural world. The Philae hymn that initially calls her ruler of the sky goes on to expand her authority, so at its climax her dominion encompasses the sky, earth, and Duat. It says her power over nature nourishes humans, the blessed dead, and the gods. Other, Greek-language hymns from Ptolemaic Egypt call her "the beautiful essence of all the gods". In the course of Egyptian history, many