Plutarch, Philopoemen
Bernadotte Perrin, Ed.

16. Soon, however, Diophanes, the general of the Achaean league, hearing that the Lacedaemonians were once more agitating for a change, determined to punish them, and the Lacedaemonians determining upon war, were throwing the Peloponnesus into confusion. Here Philopoemen tried to mollify Diophanes and put a stop to his wrath, showing him what the occasion demanded, and that since King Antiochus and the Romans were hovering about in Greece with armies so great, it behoved the general of the league to pay attention to them, and not to stir up domestic troubles, but even to be somewhat oblivious to the transgressions of his colleagues. [2] Diophanes, however, paid no heed to this advice, but invaded Laconia along with Titus Flamininus, and marched directly upon the city of Sparta. Incensed at this, Philopoemen ventured upon an act which was not lawful, nor even exactly just, but great and prompted by a great spirit. He went on past them into Sparta, and, private man though he was, shut out therefrom both the general of the Achaean league and the Roman consul, put an end to the disorders in the city, and brought the Lacedaemonians back again into the league, as they were at the outset.

[3] At a later time, however, when he had some ground for accusation against the Lacedaemonians, as general of the league¹ Philopoemen brought back its exiles to the city, and put to death eighty Spartans, according to Polybius,² or according to Aristocrates, three hundred and fifty. [4] He also tore down the walls of the city, and cutting off a large part of its territory, annexed it to Megalopolis; moreover, in the case of those who had been made citizens of Sparta by the tyrants, he removed them all into Achaia, with the exception of three thousand who would not obey him and were unwilling to go away from Sparta. These he sold into slavery, and then, as if in mockery of their fate, erected a portico in Megalopolis with the money which they brought. [5] And now, glutting his anger at the Lacedaemonians and unworthily trampling upon them in their misery, he treated their constitution in the most cruel and most lawless fashion. For he took away and abolished the system of training which Lycurgus had instituted, and compelled their boys and their young men to adopt the Achaean in place of their hereditary discipline, being convinced that while they were under the laws of Lycurgus they would never be humble.

[6] For the time being, then, owing to their great calamities, the Spartans suffered Philopoemen to cut away, as it were, the sinews of their city, and became tractable and submissive; but a while afterwards,³ having obtained permission from the Romans, they abandoned the Achaean polity, and resumed and re-established that which had come down from their fathers, so far as was possible after their many misfortunes and great degeneration.