Plutarch, Agis
Bernadotte Perrin, Ed.

11. After this, the common people took sides with Agis, but the men of wealth entreated Leonidas not to abandon them. And by prayers and arguments with the senators, whose power lay in their privilege of presenting all measures to the people, they so far prevailed that by a single vote the proposed rhetra was rejected. [2] Lysander, however, who was still ephor, set on foot an indictment of Leonidas by virtue of an ancient law which forbade any descendant of Heracles to beget children by a foreign woman, and ordained that anyone who left Sparta to settle among foreigners should be put to death.¹ After instructing others to spread these charges against Leonidas, he himself, with his colleagues, proceeded to observe the traditional sign from heaven.

[3] This is observed as follows. Every ninth year the ephors select a clear and moonless night, and in silent session watch the face of the heavens. If, then, a star shoots across the sky, they decide that their kings have transgressed in their dealings with the gods, and suspend them from their office, until an oracle from Delphi or Olympia comes to the succour of the kings thus found guilty.

[4] This sign Lysander now declared had been given him, and indicted Leonidas, and produced witnesses showing that he was the father of two children by a woman of Asia who had been given him to wife by one of the lieutenants of Seleucus; and that owing to the woman's dislike and hatred of him he had come back home against his own wishes, where he had assumed the royal dignity, to which there was then no direct successor. Besides bringing this indictment, Lysander tried to persuade Cleombrotus to lay claim to the royal dignity. [5] Cleombrotus was a son-in-law of Leonidas, and one of the royal line. Leonidas, accordingly, took fright, and fled as a suppliant to the temple of Athena of the Brazen House. His daughter also forsook Cleombrotus and became a suppliant with her father. When Leonidas was summoned to his trial and did not appear, he was deposed, and Cleombrotus was made king in his place.²