Athens is starting to create this Delian League, which is really an Athenian empire, even more insecure. And it kind of gets a little bit more intense in 464. So there are some accounts that Sparta, around this time, was already planning to invade Athens, to say, hey, these folks are getting too powerful, let's just put them in their place. But at around that time, in 464, you have a major earthquake. You have a major earthquake in Sparta. And so it demolishes large parts of the city. And when that earthquake happens, the Spartan helots, who, I guess the best way you can view them, they are slaves, and I encourage you to read more about them.