How did Pericles change the government of Athens?

Pericles was an influential person during the Peloponnesian War, (Athens' war with its archrival Sparta). He rose to power from being in the law courts, and was successful in banishing his political enemies, by means of ostracism. Ostracism was a way for an Athenian to practice democracy, aside from electing leaders. However, it also meant the banishment of someone out of Athens. Without his rivals, he was one of the most powerful men in all of Athens, and took charge over the Athenian navy and army.

Pericles also passed some laws to gain support from the masses, such as free theater plays for the poor, the rebuilding of Athens due to the war, and a law that made jury service something to be paid for. This impressed Athens' allies, and turned the Delian League (Athens and its allies) a powerful force in Greece, in some sort of empire.