Where a god and goddess are worshiped together they are not husband and wife, but mother and son. Neither does the god take pre-eminence, but the mother or goddess. This condition dates from the earliest days of society, when marriage in our sense of the word was unknown, and when kinship and Inheritance were in the female line. The Babylonian Ishtur of the Izdobar legend is a deity of this type.--W. Robertson Smith: Kinship in Ancient Arabia.