Why is it important to consider a specific film's purpose(s) when using film theory?

Film theory or cinema studies is an academic discipline that aims to explore the essence of the cinema and provides conceptual frameworks for understanding film's relationship to reality, the other arts, individual viewers, and society at large. Knowing a film's purpose will let you know how well the film has captured these aspects.

The answer is

The gregorian chant was a major cultural milestone in the middle ages. it was one of the first codified forms of music meant to be played as written, where previously it was difficult to mass-produce and disseminate any music. what's more, these chants were also some of the first examples of musical notation: the notes and bars of today's music sheets are a reflection of centuries of evolution beginning with these chants. it became official throughout the entirety of the catholic church, meaning that nearly all of europe followed this musical notation and styling.