I was expecting some dubious Bible code or play-it-backwards -type thing, but this is a cool idea. However the message is just in the sheet music, not in a piece of music at all.
The Beatles did this centuries later, announcing the demise of mate Paul McCartney when they recorded "I buried Paul" backwards on the song Strawberry Fields Forever.
https://www.theverge.com/2015/1/7/7483235/the-code-colombian...