When I traveled for a living I used to hit both new and used book stores. I was able to read a lot and was constantly buying books. I would keep them and sometimes would even mail them home if I ran out of room in my luggage. Back in the late '80s a local used book store owner was complaining about the lack of used science fiction. I went home and went through my collection. I pulled all of the books I would not be interested in rereading and gave them to her. It was over 700 books. My wife thinks the greatest thing I ever did was switch to eBooks. She thinks our house would be wall to wall books by now if I had not switched.
Apache