When they grew older and took prominent parts in public affairs, Aristides was so honest and Themistocles so tricky that they could never agree on any point. Once when Aristides had carried a case against Themistocles, who had fought hard for it, he said, "The affairs of the Athenians can never prosper unless they throw Themistocles and me into the Barathrum." This was a deep pit into which criminals were thrown headlong. Aristides did not mean to call himself or his opponent a criminal, but it was his belief that so long as two men guided by such different principles controlled Athenian politics there could be no peace or prosperity.

He was a thoroughly conscientious man, and always put himself and his personal interests out of the question in the cause of right. Even when one of his enemies was about to be condemned for a criminal action, Aristides stood up and begged the judges to give the man a chance to defend himself. When he was called upon at one time to settle a quarrel between two private citizens, one of them tried to influence him by telling him what injurious things the other had done to him. "Tell me rather, good friend," he said, "what wrong he has done you; for it is your cause, not my own, that I am judging."

Aristides, upon being appointed treasurer of the public funds, accused those who had held the office before him of having stolen some of the money. Thereupon Themistocles, who was among the accused, turned the tables upon him, and got him condemned. But the Court of the Areopagus defended him, and not only secured his release from the fine imposed, but had him chosen treasurer again. He then changed his tactics, and allowed those who were under him to steal the public money without appearing to know it. This made him very popular with the few who were benefited, and when his term of office expired they begged that he might be reappointed. When this was about to be done he thus addressed the Athenians: "While I managed your money like an honest man I was loaded with abuse, but now when I suffer a lot of thieves to rob you I become a good citizen; but I assure you I am more ashamed of the present honor than I was of the former disgrace, for I see that you prefer to oblige bad men rather than to take proper care of the treasury." Thus he turned the dishonest men against him, but gained the praise and confidence of the worthy ones.

It was about this time that a Persian fleet arrived at Marathon and began to destroy all the neighboring country. Miltiades was appointed first in command of the Athenian forces to oppose the enemy, and Aristides second. It was the custom for the generals to serve in turn, but Aristides cared so much more for the welfare of his country than he did for personal glory that, feeling Miltiades to be a more able general than himself, he gave up his right, and showed the inferior officers that he considered it no disgrace to submit to the directions of wise and able men. His example was followed by the other generals, and Miltiades took the whole command. Themistocles and Aristides fought together with such success that the Persians were driven back to their ships. The Greeks then hurried to Athens, fearing an attack there while the city was not properly defended. Aristides was left at Marathon to watch the prisoners and the spoils, and although there was much gold and silver scattered about, as well as rich garments and other booty, he neither touched them himself nor permitted his men to do so.

In course of time Aristides was called "the Just," because it was his love of justice that had more weight with the common people than any of his other virtues. Strange to say, this very surname which added to his popularity at first caused his unhappiness later, for Themistocles became envious of the weight attached to his decisions, and raised a report that Aristides was trying to abolish courts and get supreme power in his own hands. This made the Athenians so uneasy that Aristides was banished by ostracism, a proceeding that we have explained in the life of Themistocles.

When the people were inscribing their names on the shells for the ostracism, an ignorant countryman, who did not know Aristides and could not write, handed his shell to him with the request that he would write 'Aristides' upon it. "Has Aristides ever injured you?" asked the good man. "No, and I do not even know him," answered the countryman, "but it annoys me to hear him called 'the Just' all the time." Without another word Aristides wrote his name upon the shell. As he quitted Athens he raised his hands towards heaven, and prayed that his countrymen might never see the day which should force them to remember Aristides.

Three years later he was recalled because Xerxes marched into Attica, and it was feared that Aristides might go over to the enemy and induce many of his countrymen to do likewise. But he was incapable of so base a deed, and after his recall he risked his life one night by going to the tent of Themistocles with a piece of important news. "Let us lay aside our childish enmity now," he said, "and work together to save Greece. You may rule, but let me advise you to engage the enemy in the straits without delay, for the sea all around us is covered with their fleet; we cannot escape, so let us fight and prove ourselves men of courage." Themistocles replied, "I would not be outdone by you in generosity, Aristides; my future actions shall be as noble as this one of yours." He then revealed to him the stratagem he had planned, which was to send a messenger to inform the Persians that the Greeks were going to quit the straits of Salamis, and if they desired to crush them there was no time to lose. Aristides gave his hearty approval, and did all he could to aid Themistocles.

Perceiving a body of the enemy collected on a small island in the straits near Salamis, he selected the bravest of his countrymen, and went there in small boats. Challenging the Persians to battle, he slew all except a few distinguished persons, whom he took prisoners and sent to Themistocles. He received high praise for this great service, and Themistocles sought his advice still further as soon as the battle was over. He said, "You have performed a remarkable deed, Aristides, but much more remains to be done. If we sail quickly to the Hellespont and destroy the bridge there, the enemy will not be able to escape, and we can conquer them completely."

"Let us not think of such a thing," returned Aristides; "it will be better for us to devise some means of driving the Persians out of Greece without delay; for should we destroy their only means of escape, they will fight so desperately that we shall be made to suffer no end of misery." Themistocles saw the wisdom of this advice, and his busy brain soon conceived a plan not only for getting rid of the enemy, but at the same time for placing himself in a favorable light before the king. This is what he did. He sent one of the prisoners secretly to Xerxes, to inform him that the Greeks were preparing to advance to the Hellespont and destroy the bridge, but that out of regard for his royal person Themistocles was doing the very best he could to prevent it. The message had the desired effect, for Xerxes was so terrified that he hurried home, leaving Mardonius, his commander-in-chief, behind, with a force of three hundred thousand of his best troops.

Now, although the king was out of the way, the Greeks still had much to fear, for with such an army at his command Mardonius was very powerful, and constantly made his presence felt by the threatening messages he sent the various Greek tribes. By the king's advice he tried to win over the Athenians, and offered, if they would take no further share in the war, to provide them with plenty of money, rebuild their city, and make them sole rulers of Greece.

The Lacedæmonians were so afraid they might accept the proposal that they sent ambassadors to offer protection and support to their wives and children so long as the war should last. It is true that the Athenians were in dire distress, having lost their city, but they understood the offer, and were so indignant that they sent the following reply: "We could forgive the Persians, who worship gold, for supposing that we might be bought, but we are offended that Lacedæmonians, who are, like ourselves, Greeks, should imagine us capable of deserting our country under any pretext whatsoever. We are poor and wretched, but we would not exchange all the treasures either above or under ground for the liberty of Greece." This was dictated by Aristides. To the Persians he said, pointing to the heavens, "As long as that sun shines, so long will the Athenians carry on war with the Persians for their country, which has been ruined, and for their temples, which have been profaned and burnt."

When Mardonius entered Attica the second time, Aristides met him with an army, and in the first skirmish that ensued Masistius was killed. This was a terrible blow to the Persians, because Masistius was their cavalry general, and a man of remarkable courage, strength, and personal beauty. When he fell and they saw that he was mortally wounded, they fled and left the Greeks masters of the field. Their loss had not been great in numbers, but they could have spared many in place of their general, for whom they mourned very deeply. They filled the air with their lamentations, and as a sign of mourning cut off their hair, as well as the manes of their horses and mules.

After this engagement there was no fighting for a long time, because both the Persian and the Greek priests announced that all the omens promised victory to the side that stood ready for defence, but defeat to the one that made the attack. At length Mardonius felt obliged, in spite of the omens, to fall upon the Greeks, because his stock of provisions was getting very low, and he saw fresh troops joining the enemy every day and increasing their strength. So one night he gave orders for an attack to be made at break of day, thus expecting to take the Greeks unawares; and he would have succeeded had it not been for the warning the Athenians got in this way: at midnight a man approached the Grecian camp on horseback, and bade the sentinels call Aristides, to whom he had something important to say. Aristides came immediately, and the man spoke thus: "I am Alexander, King of Macedon, who for the friendship I bear you have exposed my life to save you from a surprise; for Mardonius will give you battle to-morrow, not because he expects to succeed, but because his provisions are scarce. The soothsayers give him no encouragement, but he must either risk a battle or see his whole army perish from want. Prepare yourself, but do not reveal what I have said to you."

Aristides thanked the king, and promised to tell nobody until after the battle except Pausanias, who was commander-in-chief.

As Alexander rode off, therefore, he hastened to the tent of Pausanias, who, on receiving the warning, summoned his captains and gave orders for the army to be put in battle-array.

The Athenians felt certain of victory. "Let us fight," they said, "not only in defence of our country, but that the trophies of Marathon and Salamis may belong to the people of Athens, and not to Miltiades alone." The first day passed without decisive action, and during the night the Grecian camp was removed to a spot that offered greater advantages. The Lacedæmonians made no alteration in their position, and they were the first to be attacked. For a while they allowed themselves to be slain without offering resistance, because Pausanias, who was sacrificing at a distance, could get no favorable signs, though he prayed aloud and entreated the gods with tears in his eyes. Suddenly the soothsayers announced a change and gave promise of victory. Then, with shouts and yells of delight, the Lacedæmonians rushed to the fight like wild beasts, so furious were their actions. They struck their pikes into the breasts and faces of the enemy, and killed many, though they, too, fought desperately.

Meanwhile, the Athenians, hearing of the engagement, marched back to assist the Lacedæmonians just as they were beating off the Persians. A Spartan named Arimnestus killed Mardonius by a blow on the head with a stone, the Persian camp was taken, and their men were slain by thousands.

The Greeks had gained a splendid victory, but it nearly caused their ruin, because both the Athenians and the Spartans claimed the honor of the day, and would have settled the question at the point of the sword. But Aristides did all he could to pacify the generals, and at last persuaded them to leave it to the judgment of the whole country. A council was called, and it was decided that in order to prevent a civil war the honor should be conferred neither on the Spartans nor on the Athenians, but on the Platæans. Aristides yielded at once, and Pausanias followed his example.

Both the Spartans and the Athenians built temples in honor of the victory, and sent to consult the oracle at Delphi as to what sacrifice they should offer. The answer directed them to build an altar to Jupiter, the Deliverer, but not to offer any sacrifice upon it until all the fires in the country had been put out, because they had been polluted by the barbarians. Pure fire was then to be brought from Delphi. The Greek generals visited every part of the country, and caused the fires to be extinguished, while a man named Euchidas hastened to Delphi for a fresh supply. On arriving there he purified himself with water, put a crown of laurel on his head, took fire from the altar, and hurried back to Platæa, where he arrived before sunset. But he had exhausted himself by travelling so fast, and had only time to salute his fellow-citizens and deliver the sacred fire, when he fell down dead. A monument was erected to him in the Temple of Diana, on which was inscribed, "Here lies Euchidas, who went to Delphi and back in one day."

When the first general assembly of the Greeks was called after peace had been restored, Aristides proposed that priests from all the states should meet at Platæa each year to offer sacrifices to the gods, and that every fifth year the Eleutheria, or Games of Freedom, should be celebrated there; also that ships, men, and horses should be annually supplied for war against the Persians, but that the Platæans should devote themselves to religious services, and never again stain their hands with human blood. This became a law, and the yearly procession for the sacrifice began at break of day. First a trumpeter appeared sounding the advance; then followed chariots loaded with myrrh and garlands; next a black bull, followed by young men carrying wine and milk in large vessels, jars of oil, and precious ointments. No slaves could appear in this procession, because it took place in honor of men who died fighting for freedom. Last of all came the chief magistrate of Platæa. It was considered unlawful at other times for this to touch iron or to wear any but a white garment, but on this occasion his robe was purple, and he carried a sword and a large jug. Drawing water from a spring, he washed with his own hands the little pillars of the monuments over the dead, and rubbed them with essences. Then he killed the bull upon a pile of wood, brayed to Jupiter and Mercury, and invited the brave men who had fallen in the cause of Greece to the banquet, at the same time filling a bowl with wine, and saying, "I present this bowl to the men who died for the liberty of Greece." This was the ceremony observed by the Platæans.

Another law that Aristides caused to be passed was that the Archons should be chosen from among all the Athenians, because he thought that the commons should have a voice in the government as well as the upper classes. As we have said, the people had great regard for the judgment and honesty of Aristides, and were always willing to refer to his decision. Once when Themistocles told the assembly that he had a plan to propose for the benefit of Athens, which ought to be kept secret, he was requested to tell it to Aristides. It was to burn the whole fleet of the other Greeks, so that the Athenians might become supreme rulers. Aristides was shocked at such a dishonorable proposition, and assured his countrymen "that nothing could be more advantageous than the project of Themistocles, nor anything more unjust." So the matter was dropped without the particulars being given, simply because Aristides had pronounced against it.

Eight years later Aristides was sent again to fight the barbarians, sharing the command with Cimon. His gentle, courteous manners formed such a striking contrast to the harshness and severity of the Spartan commanders, that in course of time several of the Greek nations placed themselves under him and joined the Athenians.

Aristides made himself more popular still by lessening the taxes all over the country. Notwithstanding his great influence and power, he was always poor, but he was prouder of poverty than of his trophies.

He died at Athens, well advanced in years and greatly lamented by his countrymen. Great honors were shown to his memory, and a monument was erected to him after his death.