In the cosmogony, Bel is the creator and champion of mankind, and Ea is the subterranean deep which surrounds the earth, the source of wisdom and culture; in the theology, Ea and Bel are pictured in the relation of father and son, who, in concert, are appealed to, when misfortune or disease overtakes the sons of man; Ea, the father, being the personification of knowledge, and Bel, the practical activity that 'emanates from wisdom,' as Professor Sayce,[42] adopting the language of Gnosticism, aptly puts it; only that, as already suggested, Marduk assumes the role of the older Bel.
Confining ourselves here to the earlier phases of Ea, it seems probable that he was originally regarded as the god of Eridu,--one of the most ancient of the holy cities of Southern Babylonia, now represented by Abu-Shahrein, and which once stood on the shores of the Persian Gulf.
Ur-Bau expressly calls the god the 'king of Eridu.' The sacredness of the place is attested by Gudea, who boasts of having made the temple of Nin-girsu as sacred as Eridu.[43] It is over this city that Ea watches.
The importance of the Persian Gulf to the growth of the city, would make it natural to place the seat of the god in the waters themselves.

The cult of water-deities arises, naturally, at places which are situated on large sheets of water; and in the attributes of wisdom which an older age ascribed to Ea, there may be seen the embodiment of the tradition that the course of civilization proceeds from the south.

The superiority of the Persian Gulf over the other waters of Babylon--over the two great rivers with their tributary streams and canals--would be another factor that would lead to the god of the Persian Gulf being regarded as the personification of the watery element in general.

For the Babylonians, the Persian Gulf, stretching out indefinitely, and to all appearances one with the great ocean whose ulterior shores could not be reached, was the great 'Okeanos,' that flowed around the earth and on which the earth rested.

Ea, accordingly (somewhat like En-lil), was delocalized, as it were, and his worship was maintained long after the recollection of his connection with Eridu had all but disappeared.