In the midst of this exuberant pride and good fortune, however, dark omens and prophecies crowded upon him as he approached Babylon. Of these the most remarkable was, the warning of the Chaldean priests, who apprised him, soon after he crossed the Tigris, that it would be dangerous for him to enter that city, and exhorted him to remain outside of the gates. At first he was inclined to obey; but his scruples were overruled, either by arguments from the Greek sophist Anaxarchus, or by the shame of shutting himself out from the most memorable city of the empire, where his great naval preparations were now going on. He found Nearchus with his fleet, who had come up from the mouth of the river,—and also the ships directed to be built in Phenicia, which had come down the river from Thapsakus, together with large numbers of seafaring men to serve aboard.[601] The ships of cypress-wood, and the large docks, which he had ordered to be constructed at Babylon, were likewise in full progress. He lost no time in concerting with Nearchus the details of an expedition into Arabia and the Persian Gulf, by his land-force and naval force coöperating. From various naval officers, who had been sent to survey the Persian Gulf and now made their reports, he learned that though there were no serious difficulties within it or along its southern coast, yet to double the eastern cape which terminated that coast—to circumnavigate the unknown peninsula of Arabia—and thus to reach the Red Sea—was an enterprise perilous at least, if not impracticable.[602] But to achieve that which other men thought impracticable, was the leading passion of Alexander. He resolved to circumnavigate Arabia as well as to conquer the Arabians, from whom it was sufficient offence that they had sent no envoys to him. He also contemplated the foundation of a great maritime city in the interior of the Persian Gulf, to rival in wealth and commerce the cities of Phenicia.[603] [601] Arrian, vii. 19, 5-12; Diodor. xvii. 112. [602] Arrian, vii. 20, 15; Arrian, Indica, 43. To undertake this circumnavigation, Alexander had despatched a ship-master of Soli in Cyprus, named Hiero; who becoming alarmed at the distance to which he was advancing, and at the apparently interminable stretch of Arabia towards the south, returned without accomplishing the object. Even in the time of Arrian, in the second century after the Christian era, Arabia had never been circumnavigated, from the Persian Gulf to the Red Sea—at least so far as his knowledge extended. [603] Arrian, vii. 19, 11.