The manuscript of Prelude and Fugue 1[0] is still readable almost 300 years later, goes to show how stable Western musical notation has been. Even the crossed out sections still sound fine when sight-read, but he obviously wasn't satisfied with them.
For anyone who's confused, it looks like the 5th line on the left page (measure 14) jumps to the 6th line on the right page — the pair of matching "◬" symbols. And that continues to the bottom, then jumps back to the top of that same (right) page. Also, it looks like he's freely split–
–ting measures across lines: where he finds extra horizontal space in a line, he puts a fragment of a measure there, rather than waste that space. Was paper expensive?
The article mentioned how he intentionally crammed together everything to fit on a single unfolded page so they would not need to flip the page over. This article suggests the paper may have been free for Bach though, but I suppose that doesn't account for his time spent writing or rewriting his works. https://www.bach-cantatas.com/Articles/BachPaperSize.pdf
And what about all the candles used to illuminate the parts? Not a single drop of tallow or candle wax or darkening due to the close proximity of a candle has been detected or reported regarding Bach’s original parts. Touching the parts while carrying them or turning pages would tend to leave traces, but these are not in evidence. Eventually these copies of the original parts would be collected and deliberately destroyed by Bach so that they could not be used to reconstruct the cantata.
Another aspect of all old performance materials is the utter absence of rehearsal letters ("A", "B", "C" etc.), measure numbers, little eye-glasses ("watch the first chair here"), bowings, fingerings and all the other things contemporary classical musicians need to put into their parts during rehearsal. It really makes you wonder what a rehearsal in the 18th century could possibly have been like.
And yes, I'm pretty sure Bach saved as much paper as he could. The autograph score to the Christmas Oratorio uses spare staves all over the place. This is not a page-turning consideration. An aria may coexist side-by-side with a chorus for many pages at a time to evidently prevent those 2-3 staves at the bottom of the page from being wasted.
It’s quite remarkable indeed how legible Bach’s hand is. Compare that to Beethoven’s horrific scrawl e.g.[1] Small wonder his correspondence is filled with fights with copyists and publishers over their accuracy.
That's also because he's just violently unconventional with chromaticism. There's places in late Beethoven where Urtext editors aren't sure what a specific note/accidental was intended to be: they show possibilities option A and option B (from two sources – one of which was a misprint), and even having both, the editors are undecided which one was actually the mistake. And if you study the music very carefully and think for a long time, you won't be sure either.
Everything should be digitized in case we can't control ethnic / religious violence. Riots in France are a great example of how societal collapse or cultural experiments can lead to a mass destruction of precious cultural heritage. Even more heartbreaking examples are how much of the history and treasures of the Middle East have been destroyed or desecrated by ISIS and other religious extremists.
Technology can help us save these relics as sad as it is to see their physical form perish.
Following on from this, I imagine that being able to synthesise atom-level (or at least indistinguishable) copies of priceless works of art of great significance could also provide a path towards resolving diplomatic disputes, such as in the case of the Elgin Marbles.
I hear a good number of people in contemporary musical academic circles talk about how overly simplified western music is, given its 12 tones, mostly rigid adherence to predictable rhythmic structures, and reliance on transcription. But I think the opposite of them; the simplicity of the scales and the consistency of the notation is marvelous. We can convene directly with the long-dead people who were making this stuff up 400 years ago. It's the encoding of information into a more durable storage medium than peer-to-peer.
[0] https://blogs.bl.uk/.a/6a00d8341c464853ef02b7519f7c1f200c-pi