I won't pretend to be a historian, but, weren't Plato and Aristotle key to the original rise of democracy in ancient Greece? And didn't America surpass ancient Greece about 20 years ago as the longest surviving democracy in human history?
Of course, that's just me. I may be wrong. It's more important to indoctrinate our children into revisionist history for the good of all mankind, facts notwithstanding.
If you mean republics (pure democracies are short lived) the longest lived republics was Venice (9 centuries) then Sparta and Rome. The oldest surviving republic is Switzerland.
Rome (the most similar to USA) stopped to be a real republic after/because she acquired the empire.
Page one, Soldier's Handbook (USA Army): America is NOT a democracy, America is a representative republic.
A democracy is 51% of the population doing what it wants to the other 49%. In other words, Mob Rule. The LA Riots were democracy in action.
Democratic city-states had already been establilshed in Greece, including Athens, by the time Plato and Aristotle were born. Plato in his "Republic" was actually an opponent of democracy, proposing a society ruled by an elite group of philosophers.
BTW, There was not such thing as Greek state before XIX century. (Unless you count the Eastern part of the Roman Empire after the West was conquered by the barbarians).
There was an Athenian democracy lasting very short and Spartan republic which lasted much longer than USA.