The essence of the artefact of the product of the thing.

Damn work!

I hate the word essence as well, so lets avoid it. Here we seem to be dealing with three things, their is the writing of the music, that scramble of shapes on lines, which ends up being a concherto or whatever else. Then you have the recording, the disk or casset on which the above code's outcome is documented. Finally you have memory, the personal and conversational going over of the piece of music.
We tend to associate memory with originality 'I remember going to see the yardbirds in...' and so we associate with such memorys authenticity. The recording is the original text only because it conforms to the memorys of those who saw the artist/s at the time, and in turn only because it reminds those luck enough to have been there of what they experienced.
here the issue of classical music becomes interesting. Their is no memory of it in its original form, it persits into the present only through interpretation. Yet this fails to debase the music itself, its emotional impact is still present. Indeed new memorys seem to be created as it moves through history 'I remember when Maria Callas...'
Dance music appears to be, on the contrary a music entirely dependant on memory. The halsion days between 1988-1992 being the pinacle of this memory base. The music itself does not change, but its juxtaposition by DJs and the memorys associated with such juxtapositions are the essential factors. However just as happened with classical music, those who experienced those times will meet their eventual demise. The most pressing question is weather that will undermine the recordings from those times. The answer must be no, it is the records themselves, and their continual juxtaposition in front of new people in new places will see it sustain.
re-reading this before i publish it also reminds me of anotrher essential factor, the question of the cutting edge. Classical, Jazz and dance are all representatives (get ready for a generalisation) of the musical cutting edge of their time. Memorys of the rave era are considered to contain far more cashe than the memorys that i have of indie clubbing at the contemporaniously. This is becasue indy is a more reactionary genre. the history of music theirfor seems to be a history of things that broke new ground (this is the essential nature of all chronologies I would posit).
Ultimately then it is the recordings themselves that are the essence of a piece of music. Memory, and some sense of faithfulness to an original text seem to be too vague to truly define the character of a piece of music. Indeed memory is something that constantly attaches itself to all kinds of music, made at many different times. It is our obsessional need to confer credulity on music that makes this even a question.
To offer a final answer i think that the essense of a piece of music is in how you feel when you listen to it. It is in the feelings and thoughts that it prompts. Thus the essense of the music is in the listner. But then again Barthes told us that fourty years ago.

there is no 'spirit' in different genres of music or any other art. the essence, i suppose, is the bare minimum reproduction of the performer/artist/composer's intent, the ideas/feelings/random accidents/etc.

if the 'essence' or 'spirit' of jazz is in the live performance and not the recording of same, or in the performers and instruments themselves, then is the 'e/p' of a theatrical musical act [whether we speak of opera or of gwar] also the performative iteration and not the recording of same? here we see the wishy-washy nature of the question: you cannot draw the line, any more than you can say, poet x is a very literary poet and the essence is in the text and poet y is a very electrifying poet and the essence is in the reading the poet gives, breathing life into it, so let's divide up all the poets of the world into x's and y's. how about the essence of comedy - the joke or the teller. the essence of theatre - the script or the performance. the essence of a film: if you watch a sloppily dubbed, gaudily colorized and cropped for tv version on a little set with commercial breaks, surely the spirit is still there, right? the essence is there, right?

no no, you mean, we are talking about purity. what is the key to the art form that we can use as a metaphor for what sets that art apart: jazz is improv, therefore, logically, obviously only seeing it actually improvised then disappear into the ether is the essence. and classical, that's like a language, it must be done the same every time, that's what makes classical special. and pop music, well, it's about timbre and touching up folk music into a polished or more sophisticated form, and selling it, so qed the essence is the purchasable copy.

what about all the many, many bands who say in interviews that the essence of what they are about is their live show, and not their records, the records are compromised or sound tinny?

This is becasue indy is a more reactionary genre. the history of music theirfor seems to be a history of things that broke new ground (this is the essential nature of all chronologies I would posit).

what rubbish. their are histories which valorize innovators, and histories which examine what life was like for the masses, and histories which are built around amusing stories, etc. in music history, this means that some chronologies are built around the author's idea of who was innovative, but some are built around the author's idea of what was influential and popular and meaningful to large numbers of people, and some are built around memorable events which just sort of sum up that time.

Nice packaging, yeah?

your probably right

I think there's an interesting dichotomy at work between the two main posts here; Lukey is favouring the importance of the audience and Mig is favouring the importance of the artist. Is that the essential dichotomy between popism and rockism (where popism is the opposite of rockism)? I shall have to ponder this some more. Art vs artist vs audience...

Isn't the major dichotomy, both within and between pop and rock, not more akin to "art vs. commercial product"?

Or am I still confused after the effort of trying to analyse all the subtle nuances in the lyrics to "Stand By Your Man"?

Art is commercial product and commercial product is art, I don't even think there's much point debating that anymore (at least not for me). The interesting thing I find is the division of import between artist, audience, and art itself as to where the purpose/spirit/essence/point/dasein/lasting thing/platonic soul of art lies.