Specialization of the Priesthood
” … The growth of the temple organizations along the lines above set forth naturally resulted in a differentiation of priestly functions. Besides a number of general names for priest, such as sJiangu, enu, “votary” and ummdnu (expert), with gradations of rank as indicated by the title shangu makliTihu, “high priest”, we find over thirty classes of priests recorded in the material at our disposal.
The “exerciser” (mashmashu or dsMpu) is separated from the “diviner” (baru, literally “inspector”), and these two from the “singer” (zammeru), “anointer” (pashishu), and “musician” (Ualu, lallaru, naru, etc.) and from the “snake charmers” (mushlakhkhu) , who formed a class by themselves and perhaps had other functions than the name suggests. Each of these had numerous subdivisions such as “libationist” (ramku, nisakku), “anointer” (pashishu),  “dream interpreter” and “oracle” (sha’ilu) and others such as urigallu, and the abkallu, abarakUu, whose exact functions still escape us. 
Women also took a large part as priestesses of one kind or another in the temple service  as singers, “howlers” (chanting the lamentations), musicians, exercisers and furnishing oracles. We find also several classes of holy women leading a secluded life in special homes which would correspond to our cloisters and nunneries, and who were regarded as constituting in a measure the harem of the god to whose service they were dedicated.
Some of these were “sacred prostitutes”, and it is in connection with this class of priestesses that rites were practised in the temples which, while probably regarded as purely symbolical to promote fertility among mankind and in the animal world, were unmistakably obscene, or at least degenerated into obscene rites.
In addition to the purely religious duties in connection with the temple service, the priests were also the scribes, the judges and the teachers of the people all three functions following naturally from the religious point of view involved in writing, in legal decisions and in knowledge in general.
The tradition once established, the priests continued to act as the official scribes in the case of the thousands upon thousands of legal and commercial documents that have come down to us from all periods, though, to be sure, in later days we occasionally come across a scribe who does not appear to have been a temple official.”
Morris Jastrow, The Civilization of Babylonia and Assyria, 1915, pp. 272-3.