Robert Fripp characterizes Eno's definition of ambient music as "music as ignorable as it is listenable." Muzak® is neither ignorable nor listenable, because it's so annoying. White and pink noise machines, the sleep machines that make artificial wave noises, and many other types of generative music applications (even some of the ones Eno has worked on) are ignorable, but not listenable. They are gentle and do not intrude or annoy, but if you focus on them, you get bored rapidly, because there simply isn't enough happening.
"Discreet Music" is not like that. It's non-intrusive, but if you do listen to it (and I have been listening to it a lot as I work on covering it; the version linked to in my previous post is only the first of many approaches to it) you keep hearing new things. It's fractal in that respect -- no matter how closely you look, there is more to see.
Meanwhile, I slipped out between sets at the Greenwich Village Bistro on Sunday night to browse Bleecker Street Records, where I found the 2008 reissue of (No Pussyfooting), which could also be called the "first ambient recording." It preceded Discreet Music by two years and is the first recording of the kind of looping music I'm doing now. (Yeah, yeah, Steve Reich, Different Trains, etc. No doubt a huge inspiration to Eno, but not the same thing at all.) I'll have more thoughts on that in a day or two; it's stunningly beautiful and a reminder that sometimes "remastering" really does mean something.
Finally, here's "Low Blood Sugar," my latest harmonitronica piece, nine minutes of very noisy loops, including harmonica, synthesizers, guitars and filters, all played live.