The absorption of the Greek world into the Roman empire created intellectual problems on several levels. In the first instance, Greek confidence in the superiority of Hellenic culture made explanations for the swiftness of Roman conquest all the more necessary. In accounting for Rome's success, Greeks focused on the structure and character of the Roman state, on Roman attitudes towards citizenship, and on the nature of the Roman constitution. Greeks initially attempted to understand Roman institutions and beliefs by assimilating them to paradigms within Hellenistic political thought. On the one hand, this process tended to obscure substantial differences between Greek and Roman political theory. At the same time, appreciation of Rome's relations with Italy created a means through which Greeks could imagine their own integration into the Roman community. Among the conceptual models available to Greeks of this age, only the polis provided a paradigm for a collectivity in which individuals had equal rights and toward which they directed their patriotic sentiments. That Roman Italy was not a polis did not force the coinage of new terminology: the polis formed a conceptual boundary that Hellenistic political philosophy never truly escaped. Repeated construals of Roman ideas and institutions on analogy with polis-based models ultimately forced a shift in the semantic fields of Greek political terminology and altered Greeks' conceptual archetype of the political collectivity. This process provided a framework within which Greeks could justify their wholesale participation in imperial culture and political life: they could, on these terms, argue that the gradual evolution of the world toward a single, unified empire actualized man's natural tendency to center his life around a single polis.