Histories

In this way Ariston married his third wife, after divorcing the second one. But his new wife gave birth to Demaratus too soon, before ten lunar months had passed.

When one of his servants announced to him as he sat in council with the ephors that he had a son, Ariston, knowing the time of the marriage, counted up the months on his fingers and swore on oath, “It's not mine.” The ephors heard this but did not make anything of it. When the boy grew up, Ariston regretted having said that, for he firmly believed Demaratus to be his own son.

He named him Demaratus because before his birth all the Spartan populace had prayed that Ariston, the man most highly esteemed out of all the kings of Sparta [22.4417,37.0667] (Perseus) Sparta, might have a son. Thus he was named Demaratus, which means “answer to the people's prayer.”