Classical music, part two

Last week I quoted at length from the book "A Perfect Mess" about learning the true difficulties of performing classical music (which requires constant re-tuning on the fly by instruments to keep from sounding discordant as the temperatures and other ambient factors change). This week, I'd like to add one additional piece of information about classical music, at least of the eighteenth century variety, that fundamentally changes its conception in my mind:

"The opportunity — the imperative, really — for improvisation was explicitly written into baroque compositions and in more than one way. Bach and other composers of the time rarely spelled out parts for cello, bassoon, harpsichord, and organ note-for-note, instead providing the players of these and other low-range instruments suggested chords on which they were expected to riff. Concertos contained cadenzas that challenged the soloist to cut loose from the confines of the sheet music, and the resulting long, furious improvisations were often the highlights of performances. ...

"[Bach] would embellish at length at the organ, even in the middle of church services, apparently sometimes dismaying the officiators, choirs, congregations, and others who were simply trying to get through the liturgy. In other performances, he would take musical themes tossed at him from the audience and immediately improvise around them, much in the style of a contemporary nightclub comedian. ...

"Bach and his colleagues could not have predicted that by the middle of the twentieth century the improvisational elements of their competitions, and of all classical music, would have been gradually and thoroughly excised. Composers had later filled in the bass lines and cadenzas with note-for-note versions, so that today musicians play only what's on the page, and every performance is melodically identical to every other. ... It has been a centuries-long organizing project that almost certainly would have appalled some of the very composers we most ardently lionize. ...

"Throughout this book we've seen some of the ways in which mess and disorder, in their various forms, can be a great deal less harmful than they are usually made out to be. ... Let's add one more claim: mess and disorder can be beautiful."