Leonidas, son of Cleonymus, was of the other royal house of the Agiadae, and the eighth in descent from Pausanias, who defeated Mardonius in the battle of Plataea. Pausanias was succeeded by a son called Plistoanax; and he by another Pausanias who was banished, and lived as a private man at Tegea, while his eldest son, Agesipolis, reigned in his place. He, dying without issue, was succeeded by a younger brother, called Cleombrotus, who left two sons; the elder was Agesipolis, who reigned but a short time, and died without issue; the younger, who then became king, was called Cleomenes, and had also two sons, Acrotatus and Cleonymus. The first died before his father, but left a son called Areus, who succeeded, and being slain at Corinth, left the kingdom to his son Acrotatus. This Acrotatus was defeated, and slain near Megalopolis, in a battle against the tyrant Aristodemus; he left his wife big with child, and on her being delivered of a son, Leonidas, son of the above-named Cleonymus, was made his guardian, and as the young king died before becoming a man, he succeeded in the kingdom.
Leonidas was a king not particularly suitable to his people. For though there were at that time at Sparta a general decline in manners, yet a greater revolt from the old habits appeared in him than in others. For having lived a long time among the great lords of Persia, and been a follower of King Seleucus, he unadvisedly thought to imitate, among Greek institutions and in a lawful government, the pride and assumption usual in those courts. Agis, on the contrary, in fineness of nature and elevation of mind, not only far excelled Leonidas, but in a manner all the kings that had reigned since the great Agesilaus. For though he had been bred very tenderly, in abundance and even in luxury, by his mother Agesistrata and his grandmother Archidamia, who were the wealthiest of the Lacedaemonians, yet, before the age of twenty, he renounced all indulgence in pleasures. Withdrawing himself as far as possible from the gaiety and ornament which seemed becoming to the grace of his person, he made it his pride to appear in the coarse Spartan coat. In his meals, his bathings, and in all his exercises, he followed the old Laconian usage, and was often heard to say, he had no desire for the place of king, if he did not hope by means of that authority to restore their ancient laws and discipline.
The Lacedaemonians might date the beginning of their corruption from their conquest of Athens, and the influx of gold and silver among them that thence ensued. Yet, nevertheless, the number of houses which Lycurgus appointed being still maintained, and the law remaining in force by which every one was obliged to leave his lot or portion of land entirely to his son, a kind of order and equality was thereby preserved, which still in some degree sustained the state amidst its errors in other respects. But one Epitadeus happening to be ephor, a man of great influence, and of a willful, violent spirit, on some occasion of a quarrel with his son, proposed a decree, that all men should have liberty to dispose of their land by gift in their lifetime, or by their last will and testament. This being promoted by him to satisfy a passion of revenge, and through covetousness consented to by others, and thus enacted for a law, was the ruin of the best state of the commonwealth. For the rich men without scruple drew the estate into their own hands, excluding the rightful heirs from their succession; and all the wealth being centered upon the few, the generality were poor and miserable. Honorable pursuits, for which there was no longer leisure, were neglected; the state was filled with sordid business, and with hatred and envy of the rich.
There did not remain above seven hundred of the old Spartan families, of which, perhaps, one hundred might have estate in land, the rest were destitute alike of wealth and of honour, were tardy and unperforming in the defence of their country against its enemies abroad, and eagerly watched the opportunity for change and revolution at home.
Agis, therefore, believing it a glorious action, as in truth it was, to equalize and repeople the state, began to sound the inclinations of the citizens. He found the young men disposed beyond his expectation; they were eager to enter with him upon the contest in the cause of virtue, and to fling aside, for freedom's sake, their old manner of life, as readily as the wrestler does his garment. But the old men, habituated and more confirmed in their vices, were most of them as alarmed at the very name of Lycurgus, as a fugitive slave to be brought back before his offended master. These men could not endure to hear Agis continually deploring the present state of Sparta, and wishing she might be restored to her ancient glory. But on the other side, Lysander, the son of Libys, Mandroclidas, the son of Ecphanes, together with Agesilaus, not only approved his design, but assisted and confirmed him in it. Lysander had a great authority and credit with the people; Mandroclidas was esteemed the ablest Greek of his time to manage an affair and put it in train, and, joined with skill and cunning, had a great degree of boldness. Agesilaus was the king's uncle, by the mother's side; an eloquent man, but covetous and voluptuous, who was not moved by considerations of public good, but rather seemed to be persuaded in it by his son Hippomedon, whose courage and signal actions in war had gained him a high esteem and great influence among the young men of Sparta, though indeed the true motive was, that he had many debts, and hoped by this means to be freed from them.