I got rid of most of my books when I moved to Catalonia. I miss some of them now.Hmmm. That is an interesting framework. I will have to give that some thought. I certainly keep those. But I also keep the following categories:
1- Books I might re-read one day (many, many)
2- Books I might refer to one day (many, many)
3- Books that remind me of certain times or events in my life even if I don't need to re-read them (slightly fewer)
4- Books that have come to me via dead relatives who have written in the fly leaf. I have a lot of volumes of poetry and a complete works of Shakespeare with inscriptions from relatives going back to 1870s or so (not many of these, but they feel precious)
5- Books written by relatives (some)
6- Books I intend to read (many, many and worse since my retirement party had a 'bring a book' theme, so there is literally a crate of them!)
7- Books that are duplicates of category 1, but I still can't bear to part with the original
I think it is obvious that I have a problem!