V. In the sweeping revenge of Mardonius, even private houses had been destroyed, excepting those which had served as lodgments for the Persian nobles [117]. Little of the internal city, less of the outward walls was spared. As soon as the barbarians had quitted their territory, the citizens flocked back with their slaves and families from the various places of refuge; and the first care was to rebuild the city. They were already employed upon this necessary task, when ambassadors arrived from Sparta, whose vigilant government, ever jealous of a rival, beheld with no unreasonable alarm the increasing navy and the growing fame of a people hitherto undeniably inferior to the power of Lacedaemon. And the fear that was secretly cherished by that imperious nation was yet more anxiously nursed by the subordinate allies [118]. Actuated by their own and the general apprehensions, the Spartans therefore now requested the Athenians to desist from the erection of their walls. Nor was it without a certain grace, and a plausible excuse, that the government of a city, itself unwalled, inveighed against the policy of walls for Athens. The Spartan ambassadors urged that fortified towns would become strongholds to the barbarian, should he again invade them; and the walls of Athens might be no less useful to him than he had found the ramparts of Thebes. The Peloponnesus, they asserted, was the legitimate retreat and the certain resource of all; and, unwilling to appear exclusively jealous of Athens, they requested the Athenians not only to desist from their own fortifications, but to join with them in razing every fortification without the limit of the Peloponnesus. It required not a genius so penetrating as that of Themistocles to divine at once the motive of the demand, and the danger of a peremptory refusal. He persuaded the Athenians to reply that they would send ambassadors to debate the affair; and dismissed the Spartans without further explanation. Themistocles next recommended to the senate [119] that he himself might be one of the ambassadors sent to Sparta, and that those associated with him in the mission (for it was not the custom of Greece to vest embassies in individuals) should be detained at Athens until the walls were carried to a height sufficient, at least, for ordinary defence. He urged his countrymen to suspend for this great task the completion of all private edifices --nay, to spare no building, private or public, from which materials might be adequately selected. The whole population, slaves, women, and children, were to assist in the labour. VI. This counsel adopted, he sketched an outline of the conduct he himself intended to pursue, and departed for Sparta. His colleagues, no less important than Aristides, and Abronychus, a distinguished officer in the late war, were to follow at the time agreed on.