It was one of those “one thing leads to another” email conversations which lead to the discovery of a new, but yet to be tried, author (one Elizabeth Goudge – me neither) and a superficially profound piece of advice, courtesy of the same author on the perennial problem of too many books – “one in means one out!”.
I’ve been thinking this over and come to the conclusion that this superficially simple nugget of wisdom isn’t as straight forward as it might first appear.
Problem 1: In its purest form, it’s irrational. Given that everyone starts with zero books, “one in, one out” is impossible. You could, I suppose, exclude the zero books scenario as a special case, which would mean that you would only ever own one book. Let’s call this The First Law of Book Management – okay, maybe not a law at this stage, maybe a hypothesis
If BooksCurrent <1 and BooksIn = 1 then BooksOut=0 else BooksOut=1
But its not as simple as that …
Problem 2: What if …
… It’s a three-volume novel – do we need to substitute the concept of a work for a physical book?
… You’re a guest on Desert Island Discs – do you count the Bible and Shakespeare or do they not count on the grounds that they come with the territory?
If we allow these exceptions then we get
If WorksCurrent <1 or if (DesertIslandDiscs = True and not (WorksCurrentTitle = “Bible” or “Shakespeare”)) then WorksOut=0 else WorksOut=1
Problem 3 (4,5,6,7,8 …)
Should the maximum number of books be determined by the amount of space available for storage? Should this be bookshelf space only or should it include other storage types – attics, bedside tables, floors? If bookshelves, is doubling allowed? Do we have to deduct space for non-book articles that may be stored on bookshelves such as mugs used as pencil holders, paperweights, stone eggs, elephants and, of course, camels? And DVDs – what about DVDs?
If VolWorksCurrent < (Sum((MaxShelfSpace-Sum(VolMugs,VolPaperweights, VolElephants, VolCamels), MaxBedsideTableSpace, (MaxFloorSpace-SpaceNeededForOtherStuff)) then WorksOut=0 else WorksOut=1
Problem whatever
Do library books count?
Conclusion
Time for some alternative wisdom –
“To every complex and difficult problem there is a simple and elegant solution – and it’s wrong.”
After Work 
I am currently (re) purchasing, second hand (charity shops, ex-library stock, charity shelf in Sainsburys etc.) the books I wish I hadn’t given Eddy to sell when he was raising money to go to Morrocco 6 years ago. The really brilliant thing about getting old is not being able to remember who dunnit.
You have to think about how you state the problem. I think it boils down down to how much you are comfortable storing. As you approach the limits, you either have to stop acquiring new things, increase storage or start getting rid of things. Mind you, it was the experience of decanting through several homes and eventually ending up in my present dwelling (the largest one yet for storage) that made me willing to part with some of the books I had been retaining for years. The parameters are fuzzy!
One thing I do attempt to do is make a note of books that I have formerly owned but since removed from my collection (using the LibraryThing website). This way, if I can’t find a book I’m sure I had, at least I have a hope of finding out whether it is worth keeping on looking!
Doubling up, and even trebling up, is fine. Trebling is strictly for books I bought and know I’ll never read, or books I was given by people I love(d) will never read/never read again, but with which I could never part. Chief among these is “Cuisine” a French cookery book which includes nothing in respect of mince or baked beans, just ingredients whose names I cannot pronounce.
I can’t part with Atlases either, even ones which don’t include Milton Keynes or the M25