Political theory is concerned mainly with the foundations of political community and institutions. It focuses on human nature and the moral purposes of political association. To clarify these concepts, political theorists draw on enduring political writings from ancient Greece to the present and on various writings by moral philosophers. Political theory also focuses on empirical research into the way political institutions function in practice. Here political theorists subject beliefs about political life found in important political writings to re-examination in the light of ongoing human behavior. In either case, political theory seeks to ultimately deepen political thinking and to spur citizens to responsible and creative political action.