Then Achilles went forth to battle, heartened by the inspiration of Minerva and filled with a rage and thirst for vengeance that made him irresistible. As he mounted his chariot, one of his immortal coursers was, strange to say, endowed suddenly with speech from on high and, breaking into prophecy, warned the hero of his approaching doom. But, nothing daunted, Achilles pressed upon the foe. The bravest warriors fled before him or fell by his lance.[304] Hector, cautioned by Apollo, kept aloof; but the god, assuming the form of one of Priam's sons, Lycaon, urged Æneas to encounter the terrible warrior. Æneas, though he felt himself unequal, did not decline the combat. He hurled his spear with all his force against the shield, the work of Vulcan. The spear pierced two plates of the shield, but was stopped in the third. Achilles threw his spear with better success. It pierced through the shield of Æneas, but glanced near his shoulder and made no wound. Then Æneas, seizing a stone, such as two men of modern times could hardly lift, was about to throw it,--and Achilles, with sword drawn, was about to rush upon him,--when Neptune, looking out upon the contest, had pity upon Æneas, who was sure to have the worst of it. The god, consequently, spread a cloud between the combatants and, lifting the Trojan from the ground, bore him over the heads of warriors and steeds to the rear of the battle. Achilles, when the mist cleared away, looked round in vain for his adversary, and acknowledging the prodigy, turned his arms against other champions. But none dared stand before him; and Priam from his city walls beheld the whole army in full flight toward the city. He gave command to open wide the gates to receive the fugitives, and to shut them as soon as the Trojans should have passed, lest the enemy should enter likewise. But Achilles was so close in pursuit that that would have been impossible if Apollo had not, in the form of Agenor, Priam's son, first encountered the swift-footed hero, then turned in flight, and taken the way apart from the city. Achilles pursued, and had chased his supposed victim far from the walls before the god disclosed himself.[305]