I mentioned that we had the office painted. We have built-in bookshelves in there and over time, we accumulated about 600 books. I like to use electronic books in Kindle form but some books are not available like that. The used book market and the two local libraries are good places to get a copy of a book that is too old or too specialized to be in e-format. So, over time, I get a copy of this book or that one and the total collection grows.
We have gotten rid of large numbers of books before. Getting the first pair of Kindles was a big change. We donated about 700 books then. And, I have accumulated books on statistical analysis methods, mental test theory and other secretly sexy topics that most people overlook. Books used in a tough course or that were fundamental in research project or books shared with a close friend - such books can serve as souvenirs and reminders of important milestones. As Don Aslett says in his books on decluttering, just because I donate Winer's book on analysis of variance to a library doesn't mean I didn't use his approach to good effect. Just because I get rid of the copy of "Just So Stories" Grandma gave me, doesn't mean we didn't love each other.
Most of the books I wanted to part with are not books that would be of interest to my immediate family. I asked four different retired professors if they would like to look over the books we were parting with. All four said the same thing:"Ha!" I drove the books to the public library in town. At one time, of course, the library was a collection of books and other materials. It still is, but now it is augmented by electronic communication with a large network of other libraries and teams of drivers and vehicles that carry books from a library with the book I want to my local one.
The public librarian said they are only allowed to accept up to two large bags of donated books. I gave them away but still had a large number to get rid of. The reference librarian gave me the phone number for a contact with the local retired teachers group that sells used books. Before calling, I decided to give the remaining 500+ books to the local university library. They eagerly accepted all the rest.