The system of direct self-government developed in Athens from Cleisthenes' reforms of 508/7 BCE through the death of Demosthenes in 322 BCE — the first sustained experiment in democratic rule, foundational to Western political thought, and far stranger and more radical than most modern appropriations acknowledge.
Athens invented democracy — and then executed Socrates by democratic vote, ran an empire on slave labor, denied citizenship to women and foreigners, and was eventually conquered by Macedon. Understanding Athenian democracy means holding all of this at once.