After reading the thread title, I immediately thought of researching a variant comprehend languages spell which lets you read and write 3DES-coded cyphertext (material component: the appropriate key, written on a scrap of paper).
...no, of course I'm not suffering from professional deformation!
I have a wizard with four spell books, so far the GM has been very nice and not stolen any of them- course if he did he knows what would happen with the character (settle in to make copies from all the old books I have taken from our enemies using money made from Wand and Scroll crafting/making- not the best way to run an adventuring group).
I would suggest making copies, set them in the guild hall library, try to save up some coin for the thing that you know will eventually happen- lost or stole books.
When it does happen try to find it then retreat and start making new ones.