It takes a Russian, Mikhall Bakhtin, to inform us of the tertiary nature of dialogue

1. 

   Mikhail Mikhailovich Bakhtin was a Russian philosopher, literary critic, semiotician and scholar who worked on literary theory, ethics, and the philosophy of language

Text relates to its context. 
Bakhtin claims, shape an utterance according to three variables:

1. the object of discourse, 
2. the immediate addressee,
3. and a superaddressee. 

This is what Bakhtin describes as the tertiary nature of dialogue.