"Mandaic literature, as it reaches us today, therefore, may represent a range of closely related local movements that existed in the south of late Sasanian and early Arab Iraq, distilled, studied, authorized, and preserved in a continuous tradition that has been as strong or as fragile at any given time as the priesthood. It is an amazing survival. But what comes down to us is Mandaean only by virtue of a long and changing process of defining and redefining the criteria of Mandaean ritual, authority, membership, and purity. We are unlikely ever to know many individual details of this process. What has been preserved as Mandaeism probably represents a synthesis of various local origins. The Mandaean religion does preserve many valuable ancient artefacts, but it can never have been a static and unchanging tradition. One must study their materials with this fact foremost in mind."