From a few years back:
When I talk to young composers, I tell them, I know that you’re all worried about finding your voice. Actually you’re going to find your voice. By the time you’re 30, you’ll find it. But that’s not the problem. The problem is getting rid of it. You have to find an engine for change. And that’s what collaborative work does. Whatever we do together will make us different.
... I was doing a theater piece for the Mabou Mines, it was some Beckett piece, and I wrote [Arthur Russell] a cello piece, and he liked the work and was playing it. And I came back about three months later, and I heard it and I said, “Arthur, that’s beautiful, but what happened to the piece?” And he said, “No, no, that is what you wrote,” and I said, “Arthur, it’s no longer what I wrote, it’s your piece now.” And he thought I was being upset, he apologized and I said, “No, no, no, I think we should put you down as the composer.” He had reached the point of transformation. The incremental changes had turned it into this other thing. I love the fact that he did that. And I love the fact that he didn’t know that he did it.
I read that and at first I wondered, what did Glass mean by "getting rid" of one's voice? I could tell it was the sort of statement that lent itself to any manner of willful misinterpretation.
What Glass is talking about here, particularly by way of his example, is not suppressing something you have, but not being hidebound by it. If you get comfortable with yourself and a particular way of doing things, that part of you has gone to sleep. Fusing what you have with what someone else has to offer helps shake that up. Collaboration isn't the only way to make that happen, though, but it's one of the more powerful — you have no choice but to pool your will with the other person's.
The other part of the quote, about not knowing about the transformation, also got me thinking about how it's hard not to be an imitator. Most anyone who picks up a pencil or a brush spends the first few years of doing whatever it is they're doing just copying whatever's in front of them. A necessary evil; you have to start somewhere. But over time you have to figure out how to shrug off the crutches and discard the training wheels. Nobody will take those things from you. If anything, you'll be encouraged to keep them, the better to make your work all the more familiar to those who can't be bothered to ditch their own crutches and training wheels.
I've mentioned before how I draw inspiration and creative direction as often from folks who are not writers — painters, musicians, filmmakers, actors, etc. A lot of what I draw from them is notes on the process. At the end of the day I'm still writing a book and I'm still doing it with the same little fistful of letters and punctuation marks, but it helps to find as many kinds of new eyes as possible to see that process through.