But jealous eyes were watching them, and busy tongues were wagging against that gallant race of Attica which had been foremost in the common cause against the barbarian invader. "These Athenians are dangerous neighbours," was the cry. "Let us stop them from building their wall, or Athens will become a standing menace to ourselves." Before long these murmurs reached the ears of the Spartans, and they sent envoys to dissuade the Athenians from fortifying their city. Their real purpose was disguised under the mask of anxiety for the general safety of Greece. "It is not expedient," they urged, "that the Persians, when next they come against us, should find fencéd cities which they may make their strongholds, as they have lately done in Athens and in Thebes. Cease, therefore, from building this wall, and help us to destroy all such defences, outside of Peloponnesus. If we are attacked again, we will unite our forces within the isthmus, and meet the invader from there." But Themistocles was not the man to be hoodwinked by the simple cunning of the Spartans. By his advice the Athenians dismissed the envoys, promising to send an embassy to discuss the matter at Sparta. As soon as they were gone, Themistocles caused himself to be appointed as head of the embassy, and set out at once for Sparta, instructing the Athenians to keep his colleagues back until the wall had been raised to a sufficient height for purposes of defence. Arrived at Sparta, he kept himself close in his lodging, and declined all conference with the authorities, alleging that he could do nothing without his colleagues.