There was at Athens a custom known as Ostracism. This was a law which once a year allowed the Athenians to banish for ten years any citizen who had, as they thought, assumed too much power or had become too popular. They were always afraid that such power might lead to a return of the Tyranny, and in their passionate desire to prevent that, they were often led to banish those who deserved a better reward for their services. In times of national danger, those who had been ostracized were sometimes recalled before their term of exile was over; otherwise they were not allowed to return until ten years had passed. The sentence of ostracism could not be passed unless at least six thousand votes were cast. Each vote was written on a piece of broken pottery, called an ostrakon and then placed in an urn set up in a special place for the purpose. The conflict between Themistocles and Aristeides grew so {158} great that the Athenians decided that one or the other of them must give way and leave Athens, and they decided to hold an ostracism. This resulted in the banishment of Aristeides, and Themistocles was left to carry out his aims for Athens without opposition. It is said that during the voting, an illiterate fellow, meeting Aristeides and not recognizing him, gave him his sherd and begged him to write Aristeides upon it; and he being surprised, asked if Aristeides had ever done him any injury. "None at all," said he, "neither know I the man: but I am tired of hearing him everywhere called the Just." Aristeides, hearing this, is said to have made no reply, but returned the sherd with his own name inscribed.[8] Aristeides was a noble and a conservative, and opposed to the changes which Themistocles felt to be so necessary if Athens was to keep her freedom, but he was a man whose honour has never been called in question, who gave of his best to his country without ever asking for reward, and who, when he was later recalled to power and his great rival was falling into disgrace, never, as far as is known, by word or deed, treated him in any way that was mean-spirited or ungenerous. Thanks to Themistocles, the Athenians now had a navy and a good harbour, but that would not protect them from the army of Xerxes which was advancing through Boeotia towards Attica. In their alarm, they sent messengers to Delphi to ask the {159} advice of the Oracle, but the answer they received filled them with despair. They were told to leave their home, for all was doomed to destruction, that fire and the War-God were about to bring ruin upon them, that there was no hope for them, but that they would steep their souls in sorrow. The Athenians could not believe that such a fate awaited them, and they sent again to the Oracle, entreating Apollo to look upon them with favour. At last they received the following answer, with which they returned to Athens: