
For many years I couldn’t find this quote from John Cage anywhere; it only existed on the t-shirt I bought from Rolywholyover: A Circus, a 1993 show I saw in all its venues, and which continues to live in my head. When it was at the Philadelphia Museum of Art in 1995, there was a period when I went to see it every day.

Anyway, the quote is, “Indians long ago knew that Music was going on permanently and that hearing it was like looking out a window at a landscape which didn’t stop when one turned away.”
As I remembered it, Cage’s point was that Music was like Nature, and extended beyond the frame of the window, the device which defined a landscape. But reading it now/again, I see that it’s not the window he was talking about, but the looking, or rather, the turning away. That Music exists independent of our experience of it.
With the exact text, it’s easy enough to turn up the source of Cage’s quote, which was a lecture in Boston, delivered on December 8, 1965, and recorded by WGBH. It’s archived as part of a show called, Pantechnicon, but Cage said his lecture was titled, “Rhythm, &c.,” and that he’d created it for a six-volume series of texts collected by György Kepes called, Vision + Value. [Alice Rawsthorn’s account of the architecture-heavy Vision + Value gives better context than Cage does for why Le Corbusier is so relevant.]
Cage’s buildup to this quote is a critique of the structures—musical and otherwise—we inherited, adopted, moved into without thinking, like furnished apartments:
The thing that was irrelevant to the structures we formerly made—and this was what kept us breathing—was what took place within them. Their emptiness we took for what it was: a place where anything could happen. That was one of the reasons we were able when circumstances became inviting changes in consciousness etc. to go outside where breathing is child’s play. No walls not even the glass ones which though we could see through them killed the birds while they were flying.
Even in the case of object, the boundaries are not clear. I see through what you made. If, that is, the reflections don’t send me back where I am.
I’m going to need to sit with this a bit, and it probably won’t be right now.
Pantechnicon: John Cage, 1966 [americanarchive.org]