Statuette of Isis nursing Horus, dedicated by Ankhhor, son of Perechbanebdjedet and Heretib,
ca. 664-332 BCE; Metropolitan Museum of Art
Medium: Anhydrite
Dimensions: H. 14.9 cm (5 7/8 in.); W. 5.9 cm (2 5/16 in); D. 8 cm (3 1/8 in)
"Isis was the sister-wife of the god Osiris. She is one of the main protagonists in the Osiride myth that tells of the murder of Osiris and the birth of their son Horus, then Horus' triumphal avenging of his father. According to this myth Isis was able to revive Osiris after he had been killed by his brother Seth and she became pregnant with their son Horus. After Horus’ birth, Isis nurtured her child and protected him from Seth and other dangers. Due to his mother’s care and great magical power Horus overcame all dangers and grew up to avenge his father and claim his right as the heir to the throne." (metmuseum.org)
Isis is often depicted in a long dress wearing the empty throne of her murdered husband Osiris as her headdress. In time, she became the most powerful deity in ancient Egypt. "She became so popular that all gods were considered mere aspects of Isis, and she was the only Egyptian deity worshiped by everyone in the country." (world history encyclopedia)
A few sources for more information: