My personal opinion: Music was used (back in the day) to express beliefs and pass down ideas of cultures. Nowadays it is used mostly for entertainment. But in between that there was a time of 'social reflection'. Take for example, The Classical Era of 1750. The music was mostly classical because they had influence from the middle ages and Europe's style back then. It was used for social gatherings because of the flow of the music. Ludwig Van Beethoven, for example, was incorporated in the Classical Era, and a transition to the Romantic Era (which has music with a lot of emotion). Later on though, music has been shaped into an entertainment for us.
I'm pretty sure the vanishing point is A :)
