The loftiest and purest religious conceptions of the ancient Egyptians were embodied in the myth of Isis and Osiris, which in the third millennium B.C. had already become the basis of a firmly established cult. These conceptions approached the monotheistic idea of an omnipresent god, and with them was associated a belief in a blessed immortality. Isis was the goddess of heaven, and Osiris was the Sun-god, her brother and husband, who is slain at evening by his brother Set,--the Greek Typhon,--ruler of darkness. Their child Horus, also called Harpocrates, born after the father's death, is the fresh sun of the new day, the successor and avenger of his father, the conqueror of Set; he becomes a new Osiris, while the father, ever blessed, rules in the realm of the dead, the kingdom of the West. Man, the followers of Isis taught, is an incarnation of deity, whose destiny is also his. He is himself an Osiris, and will enter upon a better state of existence beyond the grave if a favorable judgment is passed upon him in the trial given to the dead. The worship of Isis, associated with Mysteries from an early period, was reorganized by the first Ptolemy with the help of Manetho, an Egyptian priest, and Timotheus, a Greek skilled in the Eleusinian Mysteries. The purpose of the king was to unite his Egyptian and Greek subjects in one faith, and the effort was more successful than might have been anticipated. In its new Alexandrian form the worship of Isis and Osiris, or Serapis, as the latter divinity was now called, spread, not only over all Egypt, but also over the other countries in the East into which Greek culture had penetrated, and soon made its way to Italy and the West.