> What I'm wondering about is how the music itself, the music theory behind the composition, relates to the organisation of society, particularly when different cultures and societies in different time periods develop very different ways of relating music to certain emotions and social events, the use of completely different scales and tonalities between different cultures, and how this can be explained with a marxist analysis?
It wont be a strict marxist analysis, but a materialist one. A Concise History of Western Music thesis is that the ways of relations between the time and the society (obviously mediated with technical means of production) explain the diferences in music, between places and ages. Paul Griffits has another books on premodern music, should take a look.
>Partimenti evolved in the late 17th century in educational milieus in Bologna, Rome, and Naples, originally out of the tradition of organ and harpsichord improvisation.[6] The earliest dated collection of partimenti with a known author is attributed to Bernardo Pasquini in the first decade of the 18th century
4 part writing was already well-developed by the 16th century, and evolved from 3 part writing, which in turn evolved from 2 part writing.
Something like this would be a good start:
https://www.amazon.com/History-Western-Music-Tenth/dp/0393668177
TBH I've been listening to music since I was a kid in the 1970s and while I feel I've got a general idea of where in time certain musical trends are I also feel like I still know nothing about a lot of it.
When I was 16 I'd just get recommendations off people I knew.
As we drifted apart I ended up using Making Music's Influences column and this eventually evolved into me using various naff lists just to get a feel for what was out there.
At one point I used Allmusic's 5 star reviews (they're in a spreadsheet here - it'll be there until I bin the thing or tidy it up in a moment of misguided house cleaning), the 1000 albums to listen to before you die, and the Rolling Stones top 100 to try and get some feel for stuff I might have missed.
In the end I just gave up because I realised there's far more music than you can ever listen to in one lifetime and it was turning into less a journey of discovery and more of a chore to try and keep up with what was happening now, while trying to fill in gaps.
If you want an appreciation for the general sweep of Western Art Music history then a historical survey book will help you out. The Cambridge guide to Western Music is pretty short and relatively cheap. If you want something more expansive then the Norton History of Western Music will do that job pretty well.
None of these will tell you anything about the various kinds of world music though - nothing about the massively complex world of African music, South American music, or Asian music - and they don't cover most popular genres so you won't find out anything about Appalachian folk tunes, or British Music Hall or anything like that.
I think my general advice would be to try and keep an open mind, ignore "artists like X" recommendations and pick things more-or-less at random.
In fact you could turn it into a game.
Pick a country.
Afghanistan's in the news a lot atm, so, let's try that.
Go to Wikipedia and find Afghanistan.
Search in page for "music".
If it redirects you to another page that deals with the music of that country, go there.
Find a term. Let's go with "Klasik".
Go you YouTube & search for "Afghanistan Klasik".
I'm going to pick the 2nd video that appears.
Now you know at least something about the sound-world of Afghanistani music.
As you start to listen to music from nearby geographical areas you'll start to spot musical ideas that sound similar. Dig into the history (back to Wikipedia initially - if something really lights your fire look at the reference section and dig around in that for what you can find/afford). Bit of reading, bit of listening.
Do a year or two of that and you'll realise - no matter how wide your experience - that you've spent your entire life stuck in a musical box.
To my knowledge there's 2000-odd years of music we know about and can translate into modern music notation with varying degrees of accuracy And the world is vast and wide.
So I wouldn't worry about catching up, but a little education never hurt anyone : )