Book mysteries

We ended up with quite a collection of early 19th century old books after ranging all our families' possessions. Out of that array of topics, from Russian poetry, to logarithms tables, Latin dictionaries, encyclopedias, novels, a sexual education book (amazingly realistic for the early 1900's!), this one is the biggest mystery for me.
As you see, it's an English literature book, that I found very interesting to see because I never knew literature can be studied with graphics and plot diagrams.
But the mystery is this: it's underlined and annotated, but as far as we know nobody in both our families ever knew English. It was not often taught here around 1918- at all!
Who studied it so deeply? And why was the book kept for so long?
We will probably never know, as the book cannot tell us.