I am a librarian, too, and I go through my books at least once a year and "weed" the ones that I don't want or look at. I give them to the library book sale or pass them along to guild members. I try to confine myself to one shelf of books but they do spill out onto another one. I also loosely organize them by subject. I keep patterns in "Princeton files" and confine them to 3 which I keep near the books. I weed through those every year, too, and give the ones I don't want to the pattern library that the guild has and I schlep to/from meetings if no one borrows it.