And you might say, okay, maybe they're somewhat concerned about the Persians, but you could also argue that they're somewhat concerned about the Spartans, who are famous for having this very powerful army. And so they start the construction on what's often called the Long Wall, and it's a way for them to have access to the sea and to protect their city in the event of a siege. Now, if you take the other side, if you think about what's going on in the minds of the Spartans, they are thinking, okay, you know, for a long time, we were really the dominant military power. But what we've just seen with the Greco-Persian Wars is this Athenian navy is actually quite strong. And in some ways, in fact, in a lot of ways, you could argue that they're the ones that were able to beat off the Persians at Salamis, that the navy was essential there. So Sparta is feeling a little bit threatened, and in particular, they don't like the idea of this wall, because here you have the city-state Athens with this very strong navy. Now they're building a wall.