Similar to their Rosetta Stone disk, if we store enough data to decide just the first content. Like TOC, some intros, etc, and some instructions on how to build a rudimentary device to read/decide the next, more compressed, digital bits of info, so that after accessing this second level data, you could gradually build better devices to decode more if the library.
So some data can remain unretrievable without going through the first steps, but it would still be accessible.
