As someone who used indexes a lot during my undergrad and graduate work I never stopped to think that they weren't just a thing that books always had. Or that it isn't always the author who creates the index. Or that someone could influence users through what they include in an index. This is a wonderful history of an unsung hero of research.

Also, I feel both seen and scolded by historical figures because I am unfortunately often the student who uses an index without reading the work.