He was a most determined champion for justice, not only against feelings of friendship and favour, but wrath and malice. Thus it is reported of him that when prosecuting the law against one who was his enemy, on the judges after accusation refusing to hear the criminal, and proceeding immediately to pass sentence upon him, he rose in haste from his seat and joined in petition with him for a hearing, and that he might enjoy the privilege of the law. Another time, when judging between two private persons, on the one declaring his adversary had very much injured Aristides; "Tell me rather, good friend," he said, "what wrong he has done you; for it is your cause, not my own, which I now sit judge of." Being chosen to the charge of the public revenue, he made it appear, that not only those of his time, but the preceding officers, had alienated much treasure, and especially Themistocles-"Well known he was an able man to be, But with his fingers apt to be too free."Therefore, Themistocles associating several persons against Aristides, and impeaching him when he gave in his accounts, caused him to be condemned of robbing the public; so Idomeneus states; but the best and chiefest men of the city much resenting it, he was not only exempted from the fine imposed upon him, but likewise again called to the same employment. Pretending now to repent him of his former practice, and carrying himself with more remissness, he became acceptable to such as pillaged the treasury by not detecting or calling them to an exact account. So that those who had their fill of the public money began highly to applaud Aristides, and sued to the people making interest to have him once more chosen treasurer. But when they were upon the point of election, he reproved the Athenians. "When I discharged my office well and faithfully," said he, "I was insulted and abused; but now that I have allowed the public thieves in a variety of malpractices, I am considered an admirable patriot. I am more ashamed, therefore, of this present honour than of the former sentence; and I commiserate your condition, with whom it is more praiseworthy to oblige ill men than to conserve the revenue of the public." Saying thus, and proceeding to expose the thefts that had been committed, he stopped the mouths of those who cried him up and vouched for him, but gained real and true commendations from the best men.
When Datis, being sent by Darius under pretence of punishing the Athenians for their burning of Sardis, but in reality to reduce the Greeks under his dominion, landed at Marathon and laid waste the country, among the ten commanders appointed by the Athenians for the war, Miltiades was of the greatest name; but the second place, both for reputation and power, was possessed by Aristides; and when his opinion to join battle was added to that of Miltiades, it did much to incline the balance. Every leader by his day having the command in chief, when it came to Aristides's turn he delivered it into the hands of Miltiades, showing his fellow-officers that it is not dishonourable to obey and follow wise and able men, but, on the contrary, noble and prudent. So appeasing their rivalry, and bringing them to acquiesce in one and the best advice, he confirmed Miltiades in the strength of an undivided and unmolested authority.
For now every one, yielding his day of command, looked for orders only to him. During the fight the main body of the Athenians being the hardest put to it, the barbarians, for a long time, making opposition there against the tribes Leontis and Antiochis, Themistocles and Aristides being ranged together fought valiantly; the one being of the tribe Leontis, the other of the Antiochis. But after they had beaten the barbarians back to their ships, and perceived that they sailed not for the isles, but were driven in by the force of sea and wind towards the country of Attica, fearing lest they should take the city, unprovided of defence, they hurried away thither with nine tribes, and reached it the same day. Aristides, being left with his tribe at Marathon to guard the plunder and prisoners, did not disappoint the opinion they had of him. Amidst the profusion of gold and silver, all sorts of apparel, and other property, more than can be mentioned, that were in the tents and the vessels which they had taken, he neither felt the desire to meddle with anything himself, nor suffered others to do it; unless it might be some who took away anything unknown to him; as Callias, the torch-bearer, did. One of the barbarians, it seems, prostrated himself before this man, supposing him to be a king by his hair and fillet;and, when he had so done, taking him by the hand, showed him a great quantity of gold hid in a ditch. But Callias, most cruel and impious of men, took away the treasure, but slew the man, lest he should tell of him. Hence, they say, the comic poets gave his family the name of Laccopluti, or enriched by the ditch, alluding to the place where Callias found the gold. Aristides, immediately after this, was archon;although Demetrius, the Phalerian, says he held the office a little before he died after the battle of Plataea. But in the records of the successors of Xanthippides, in whose year Mardonius was overthrown at Plataea, amongst very many there mentioned, there is not so much as one of the same name as Aristides; while immediately after Phaenippus, during whose term of office they obtained the victory of Marathon, Aristides is registered.