The Greeks.--The two prominent states of Greece.--Greek kings.--The two kings of Sparta.--Origin of the custom of two kings.--The twins.--The Delphic oracle consulted.--Plan for ascertaining the eldest.--Civil dissensions.--Two lines established.--Character of the Spartans.--Their lofty spirit.--The Athenians.--The city of Athens.--Sparta and Athens defy the Persians.--Earth and water.--Spirit of the Spartans.--The blank tablets.--Leonidas.--His wife discovers the writing on the tablets.--The three spies.--Alarm at Athens.--The Greeks consult the Delphic oracle.--The responses.--Various interpretations of the oracle.--The Athenian fleet.--Themistocles.--Proposed confederation.--Council of Spartans and Athenians.--The Argives reject the propositions of the Spartans.--Embassy to Sicily.--Demands of Gelon.--The embassadors go to Corcyra.--The River Peneus.--The Vale of Tempe.--Straits of Thermopylae.--Question to be decided.--Messengers from Thessaly.--Negotiations.--Decision to defend the Olympic Straits.--Sailing of the fleet.--Advice of the King of Macedon.--The Greeks fall back to Thermopylae.--Xerxes visits Thessaly.--Beautiful rural scene.--Conversation of Xerxes at the Olympic Pass. We must now leave, for a time, the operations of Xerxes and his army, and turn our attention to the Greeks, and to the preparations which they were making to meet the emergency. The two states of Greece which were most prominent in the transactions connected with the invasion of Xerxes were Athens and Sparta. By referring to the map, Athens will be found to have been situated upon a promontory just without the Peloponnesus, while Sparta, on the other hand, was in the center of a valley which lay in the southern part of the peninsula. Each of these cities was the center and strong-hold of a small but very energetic and powerful commonwealth. The two states were entirely independent of each other, and each had its own peculiar system of government, of usages, and of laws. These systems, and, in fact, the characters of the two communities, in all respects, were extremely dissimilar.