Cleisthenes ( ; ), or Clisthenes (c. 570c. 508 BC), was an ancient Athenian lawgiver credited with reforming the constitution of ancient Athens and setting it on a democratic footing in 508 BC. For these accomplishments, historians refer to him as "the father of Athenian democracy." He was a member of the aristocratic Alcmaeonid clan. He was the younger son of Megacles and Agariste making him the maternal grandson of the tyrant Cleisthenes of Sicyon. He was also credited with increasing the power of the Athenian citizens' assembly and for reducing the power of the nobility over Athenian politics. In 510 BC, Spartan troops helped the Athenians overthrow the tyrant Hippias, son of Peisistratus. Cleomenes I, king of Sparta, put in place a pro-Spartan oligarchy headed by Isagoras. But his rival Cleisthenes, with the support of the middle class and aided by democrats, took over. Cleomenes intervened in 508 and 506 BC, but could not stop Cleisthenes and his Athenian supporters. Through Cleisthenes' reforms, the people of Athens endowed their city with isonomic institutions—equal rights for all citizens (though only free men were citizens)—and established ostracism as a punishment. Biography Historians estimate that Cleisthenes was born around 570 BC. Cleisthenes was the uncle of Pericles' mother, Agariste, and of Alcibiades' maternal grandfather, Megacles. Cleisthenes came from the family of the Alcmaeonidae. He was the son of Agariste and grandson of Cleisthenes of Sicyon. Unlike his grandfather who was a tyrant, he adopted politically democratic concepts. When Pisistratus took power in Athens as a tyrant, he exiled his political opponents and the Alcmeonidae. After Pisistratus' death in 527 BC, Cleisthenes returned to Athens and became the eponymous archon. A few years later, Pisistratus' successors, Hipparchus and Hippias, again exiled Cleisthenes. In 514 BC, Harmodius and Aristogeiton assassinated Hipparchus, causing Hippias to further harden his attitude towards the people of Athens. This led Cleisthenes to ask the Oracle of Delphi to persuade the Spartans to help him free Athens from tyranny. Cleisthenes' plea for assistance was accepted by the Oracle as his family had previously helped rebuild the sanctuary when it was destroyed by fire. Rise to power With help from the Spartans and the Alcmaeonidae (Cleisthenes' genos, "clan"), he was responsible for overthrowing Hippias, the tyrant son of Pisistratus. After the collapse of Hippias' tyranny, Isagoras and Cleisthenes were rivals for power, but Isagoras won the upper hand by appealing to