Identity integration both produces and is facilitated by more complex and inclusive identity structures. The key experience is that of a frustration or crisis that can be resolved only through the development of more inclusive structure. In order for people to develop more inclusive structures, the frustration they experience in their structure must not threaten their sense of self to the point that they revert to even simpler structures in order to maintain their identities. In addition to supporting impulsive identity through its expressive function, language supports the imperial, ongoing self through the permanence of its substantives and through verb tenses denoting ongoing states of being as well as past and future states. Modernity, however, confronts the interpersonal identity structure of traditional orders with a crisis: it demands that individuals occupy multiple social roles and integrate the often quite diverse values and dispositions associated with those roles.