Pericles is right to say that Athens exceeded what was expected of her, because they knew they had gone where no political system had gone before. They had created a complex agrarian society with citizen participation in government and laws to protect the people.
Two caveats apply here, however. Pericles ignores the might of Sparta during a time when the two Poleis were at war. He derides the unique Spartan oligarchy which, in fact, was successful as a rival political system. Secondly, he hides Athenian imperialism under the cloak of “adventurous spirit.” Imperialism was a direct cause of the Peloponnesian War which Athens would lose.