Themistocles believed that the chief thing necessary for Athens was a fleet, and he persuaded the Athenians, though with great difficulty for they could not at first see the necessity, to build ships. There was not very much money in Athens just then, and without money ships could not be built. But at this critical time, an unexpectedly large sum of money was paid into the public treasury. This was the revenue from the silver mines at Laurium in the south of Attica, which the Athenians were intending to divide amongst themselves. "Then Themistocles persuaded them to give up this plan of division and to make for themselves with this money two hundred ships." This they did, and they also improved the harbour of Athens, and
henceforward, little by little, turning and drawing the city down towards the sea in the belief that with their ships they might be able to repel the Persians and command Greece, Themistocles, so Plato tells us, turned the Athenians from steady soldiers into mariners and seamen and gave occasion for the reproach against him, that he took away from them the spear and the shield and bound them to the bench and the oar.[[6]]
Themistocles did not accomplish this without opposition. He had a rival in Athens, Aristeides, a man who had grown up with him and played with him as a boy, but who had always taken the opposite sides in whatever they were doing. Unlike Themistocles, Aristeides belonged to a noble family, and whenever Themistocles took the side of the people, Aristeides favoured the nobles. Even as boys they
were at variance with each other, and they soon made proof of their natural inclinations; the one being ready, adventurous and subtle, engaging readily and eagerly in everything; the other of a staid and settled temper, intent on the exercise of justice, not admitting any degree of falsity or trickery, no not so much as at his play.[[7]]
Of all his virtues, it was the justice of Aristeides which most appealed to the people; it never failed under any circumstances, and so they gave him the surname of the Just.
Now Aristeides believed that the building of a navy for Athens was too great a change from the former policy of the city. The Athenians had won the battle of Marathon and had thereby secured their reputation as soldiers, and he thought it very ill-advised and dangerous to depart from the old traditions and to put all their strength into war ships. Themistocles thought otherwise, and the two leaders came into violent conflict with each other.
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 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.