Who is the master, where does the repertoire come from?

The repertoire, like the Classic Literature of books, is a cultural artifact. There may have been whole traditions and collections of the music of ancient cultures that have vanished forever in the pillage and neglect of ruins of dead cultures, and music is certainly a most fragile product with no means to store it in a recoverable form until very recently and no universal way to express it for posterity.

So, how do we get a repertoire? The serious music repertoire is actually pretty small as compared with the total popular and folk music, certainly in the amount recorded. For recording, that may reflect market share, but there is another factor. What is played in selected by the musicians who play it. That seems at once obvious, but it also reflects a selection process by what teachers of performance and performers can play, what is playable, and prefer to play. Certiantly any ensemble has some leader, explicit or otherwise, who selects what they will play. Usually, 100 piece orchestras do not debate what they play, that is the choice of the music director, usually also its conductor, who is partly influenced by what he think his patrons and audience want to hear.