As an opera conductor I have two main tasks; one is to help the singers sing as well as they possibly can, and two, to be the composer’s advocate, and I take that role very seriously.Who knew that conductor's did more than just wave their arms around?!?!
Seriously, though. This is a very sound approach to conducting. I can imagine composers sitting at their desk (or computer these days) with a great sense of hope. Hope that what they're writing sounds exactly as they hear it with their mind's ear. They requires, though, that the musicians know how to handle their instruments well and that the composer can bring those musicians together into a single unit in such a way that it communicates that written music as they believe the composer intended... as Walker says, they need to be the composer's advocate.
I actually think this has applications in places other than conducting as well. One such place is preaching. Let's consider applying this quote to that task. The preacher is someone who (1) helps the congregation live as well as they possibly can and (2) is the advocate of the writer of the text. Some may prefer to reverse the order, or perhaps consider them two sides of the one coin, but I think that it summarises the preacher's task very well.
This requires a communal understanding of the church. It requires the rejection of any form of individualism, since the preacher requires the author of the text, and the author the preacher. In much the same way that the composer needs the musicians and the conductor to transform the notes on the page into beautifully and carefully arranged sounds in the air, so too the writer of the text needs the reader of the text and the preacher to be their advocate to the people.
Fortunately, the preacher has the advantage that the text is inspired by the Holy Spirit and he is available to inspire its reading and exposition as well. So writer and preacher rely upon him to illuminate their hearts; for the purpose of placing the words on the page, and the words in their mouth. Of course, they're not the only two involved here. There are the hundreds of scholars throughout the ages who have faithfully translated the text, the scribes who copied it, printers, binders, copiers, readers and even the 80-something-year-old faithful servant of God who walks the pews before everyone has arrived on a Sunday putting Bibles on the seat. All so that when we gather around the Word of God to hear his words speak to us again, we can indeed "hear what the Spirit is saying to the churches". This is both an immense privilege and an awesome responsibility.
"May these words of my mouth and this meditation of my heart be pleasing in your sight, LORD, my Rock and my Redeemer." Psalm 19:14
P.S. For those interested in hearing the interview with Andrew Walker you can access it here. The quote is at about the 10:00 minute mark.