One of the ancient mystery cults, the Isiac mysteries focused on the myth of Isis, sister and wife of the Egyptian god Osiris. They emerged in Hellenistic Egypt sometime in the second or third century BCE as Greek settlers in Egypt adopted the worship of the local goddess but reshaped her rites into forms more familiar to them. By the first century of the Common Era Iseums (temples of Isis) offering initiation into her mysteries could be found over most of the Roman Empire; even Londinium in the backwater province of Britannia boasted one. See mysteries, ancient.
The myth around which the Isiac mysteries built their initiations began with the death of the vegetation god Osiris at the hands of his brother Set, god of the sterile desert. Isis searched for the body of her husband and finally recovered it in the distant town of Byblos in Phoenicia. Returning with the body to the banks of the Nile, she brought Osiris back to life and coupled with him, begetting a son, Horus. Not long afterwards, Set’s minions found Osiris in his hiding place and killed him a second time, hewing him to pieces and throwing them in the Nile to prevent a second resurrection. Osiris then became the god of the dead; Isis gave birth to Horus and raised him to manhood in secret, and Horus then slew Set and became the ruler of Egypt.
One of the core symbols of the Isiac mysteries was the image of Isis suckling the infant Horus. Ironically, when the Christian Church seized power in the Roman world during the fourth century CE, some statues of this sort were renamed, and became images of the Virgin Mary and the baby Jesus. Some of the famous “black Madonnas” of southern Europe, according to recent art historians, may actually be “black Isises” preserved in this way.
SOURCE:
The Element Encyclopedia of Secret Societies : the ultimate a-z of ancient mysteries, lost civilizations and forgotten wisdom written by John Michael Greer – © John Michael Greer 2006