The end of the Peloponnesian War allowed the Greek city-states to rethink their political systems and reform their alliances and federal constitutions to avoid the mistakes of the previous century. However, they found it difficult to reconcile the formation of new federal leagues with their deeply rooted idea of autonomy: the view that each independent polis should live under its own laws. John Lewis explains the nature of this tension and contrasts how Sparta and Athens projected (and reformed, in the case of the latter) their political vision.