[Footnote 2: Pausanias tells us that he saw at Delphi a statue of this Scyllias, which had been erected by the Amphictyonic Council. A statue of his daughter Hydna had formerly stood next to it, but had been carried off by Nero. The two were famous divers, and some marvellous legends had gathered about them. Pausanias was told that they had dragged away the anchors and moorings of the Persian ships during the storm, and so aggravated the disaster. Herodotus had heard a yet more marvellous story of how Scyllias had dived the whole distance, nearly ten miles, between the Persian station and the Greek, but adds characteristically, "My own opinion is that he made the passage in a boat."] IV THE WOODEN WALLS The retreat of the Greek forces from Thermopylæ and Artemisium left Athens without defence. There had been a promise that an army of the allies should make a stand against the invaders in Bœotia. No attempt was made to keep it. The only plan of defence that commended itself to the Peloponnesian States was to fortify the Isthmus of Corinth--and all the states outside the Peloponnesus, Athens excepted, were either pro-Persian or indifferent. As Athens was unwalled, there was no question of defending it; the only thing that could be done was to save as much life and property as was possible. For this the time was short, and might have been shorter than it actually was, for the Athenians had six days in which to transport their belongings to a place of safety, though the distance to be traversed by the invaders was not more than ninety miles. All the women, children, and persons incapacitated by illness or old age were put on shipboard, and carried either to Trœzen, a friendly city in the peninsula of Argolis, which had some tie of kinship with Athens, to Ægina, which was but ten miles away, or to Salamis, which was even nearer. The Athenians begged the allies to remain in the neighbourhood till the work of transport was accomplished, and Salamis happened to be the most convenient spot for this purpose. The whole fighting strength of Athens was now embarked in its fleet. Years before, Themistocles, with a sagacity and prescience that seem almost miraculous, had counselled his countrymen to spend all their available resources in building ships. And only a few months before, the oracle of Delphi had advised the Athenians to trust in their "wooden wall," a phrase which this same statesman had interpreted as meaning the ships. No one, we may believe, knew better what it meant, as he had probably suggested it. The time had now come to put this counsel into practice. Every able-bodied Athenian took service in the fleet, the wealthy aristocrats, known as the "knights," setting the examples by hanging up their bridles in the temple of Athené.