It seems that one of the ancient and long-venerated gods of the Egyptians was a deity named Serapis.  He had been, among other divinities, the object of Egyptian adoration ages before Alexandria was built or the Ptolemies reigned.  There was also, by a curious coincidence, a statue of the same name at a great commercial town named Sinope, which was built upon the extremity of a promontory which projected from Asia Minor into the Euxine Sea.  Sinope was, in some sense, the Alexandria of the north, being the center and seat of a great portion of the commerce of that quarter of the world.

The Serapis of Sinope was considered as the protecting deity of seamen, and the navigators who came and went to and from the city made sacrifices to him, and offered him oblations and prayers, believing that they were, in a great measure, dependent upon some mysterious and inscrutable power which he exercised for their safety in storms.  They carried the knowledge of his name, and tales of his imaginary interpositions, to all the places that they visited; and thus the fame of the god became extended, first, to all the coasts of the Euxine Sea, and subsequently to distant provinces and kingdoms.  The Serapis of Sinope began to be considered every where as the tutelar god of seamen.

Accordingly, when the first of the Ptolemies was forming his various plans for adorning and aggrandizing Alexandria, he received, he said, one night, a divine intimation in a dream that he was to obtain the statue of Serapis from Sinope, and set it up in Alexandria, in a suitable temple which he was in the mean time to erect in honor of the god.  It is obvious that very great advantages to the city would result from the accomplishment of this design.  In the first place, a temple to the god Serapis would be a new distinction for it in the minds of the rural population, who would undoubtedly suppose that the deity honored by it was their own ancient god.  Then the whole maritime and nautical interest of the world, which had been, accustomed to adore the god of Sinope, would turn to Alexandria as the great center of religious attraction, if their venerated idol could be carried and placed in a new and magnificent temple built expressly for him there.  Alexandria could never be the chief naval port and station of the world, unless it contained the sanctuary and shrine of the god of seamen.

Ptolemy sent accordingly to the King of Sinope and proposed to purchase the idol.  The embassage was, however, unsuccessful.  The king refused to give up the god.  The negotiations were continued for two years, but all in vain.  At length, on account of some failure in the regular course of the seasons on that coast, there was a famine there, which became finally so severe that the people of the city were induced to consent to give up their deity to the Egyptians in exchange for a supply of corn.  Ptolemy sent the corn and received the idol.  He then built the temple, which, when finished, surpassed in grandeur and magnificence almost every sacred structure in the world.