"The importance of the Peloponnesian War for our purposes is obvious. First, it—on Thucydides's account of it—exemplifies the strengths and weaknesses of democracy in ways that every succeeding age has seized on. On the one side, the resourcefulness, patriotism, energy, and determination of Athens were astonishing; on the other, the fickleness, cruelty, and proneness to dissension were equally astonishing. (…) Second, it reveals one major reason for the ultimate failure of the Greek states to survive the rise of the Macedonian and Roman empires. Greek city-states were conscious both of being Greek and of their own narrower ethnicity: Athenian, Theban, Spartan."