English isn't my strong suit but it could probably reveal a lot about the composer's authorial context during the particular era.
This is more for Module A for Advanced English in particular but for example I did Shakespeare's Richard III and Pacino's film Looking for Richard and I said how the textual form of a docudrama for Pacino's text accommodates for the postmodern 20th century American audience in which the rise of visual mediums permeated. And I guess I said how the use of a play accommodated for the Elizabethan era and stuff like that. This is just really general and my English isn't too good anyways so don't take my ideas too seriously.
Asides from context, it could probably also act as a mechanism to deliver a particular purpose that the composer wishes to convey. For example in a Petrarchan sonnet, the composers might wish to elucidate a transformative experience or revelation. In a speech, the author wishes to convey a particular idea etc
Anyways yeah hope that helped.