Osiris changed what Egyptian kings expected to happen after death
Old Kingdom pharaohs believed that at death they would rise to join the sun god Ra in the sky. Then the cult of Osiris spread, the god murdered by his brother and brought back to life, and kings began to hope instead that they would merge with him and share his resurrection.
Osiris ruled over fertility, farming, vegetation, the dead and rebirth. Artists showed him bearded like a pharaoh, his legs partly bound in mummy wrappings, wearing the tall atef crown and holding a crook and flail; he was among the first figures linked with the mummy wrap. His titles included Lord of Silence and Khenti-Amentiu, Foremost of the Westerners, the west being the land of the dead.
In his myth, his brother Set killed him and scattered his body. His sister and wife Isis, helped by their sister Nephthys, searched Egypt for the parts, recovered all but one, and wrapped him so he could live again. Horus the Younger was said to be his son, conceived after his death. Genealogies sometimes named him the firstborn of Nut, goddess of the sky, and Geb, god of the earth, and blending with the god Iah tied him to the Moon as well.
Resurrection linked him to the rhythms of nature: sprouting crops, the yearly Nile flood, and the dawn reappearance of Orion and Sirius at the new year. The kings' hope of joining him worked through imitative magic, repeating his story to gain eternal life.
His worship is first attested in the middle of the Fifth Dynasty, in the 25th century BCE, though the Foremost of the Westerners title reaches back to the First Dynasty. Much of what is known comes from the Pyramid Texts, later New Kingdom documents such as the Shabaka Stone, and centuries afterwards Greek writers including Plutarch.
Source: Osiris
