You know “do re mi fa sol la ti”? This system for naming notes was invented by a guy named Guido of Arezzo around 1000 AD. But he only named the first 6 notes, because the whole idea of a 7-note scale wasn’t very important for him: instead he used hexachords. And instead of “do” he used “ut”—because these were words in a Latin song.
This is a companion discussion topic for the original entry at https://johncarlosbaez.wordpress.com/2024/01/15/giovanni-battista-doni/