Over the millenia, humans have collected and catalogued the accumulated knowledge of civilization in libraries. These knowledge depots are of the utmost importance for us to learn about the preceding generations. How they lived, what they ate, why did they go to war, and against whom, what poetry, songs and music did they have, what did they wear, what their dwellings looked like, and much more.
Cuneiform on clay tablets, and Hieroglyphs on stone
Take for instance the palace library of Ashurbanipal, from around 2.7 millenia ago. It is partially preserved, and contained texts as famous as the Epic of Gilgamesh, Enuma Elish creation story, astronomical observation of Venus, treaties, and far far more material preserved for posterity.
The same goes for the Amarna letters, which gives us insight into the diplomacy of Egypt with the Levant in the second half of the 2nd millenium BC. Add to that all the inscriptions on temples and inside tombs, as well as discarded ostraca.
Not only is information in libraries and official archives important, but also mundane everyday things, such as accounting records and school exercises in cuneiform from ancient Mesopotamia, school exercises from Egypt, songs, religious hymns, merchant letters, ...etc.
But all this knowledge is certainly perishable.
Papyrus and World Knowledge in a Library
Now, think about the Library of Alexandria.
The knowledge in the Library of Alexandria stored information on papyri, a medium that does not withstand fire nor humidity.
The digital age, and the information loss
Now think of our current digital age:
Ten years ago I wrote an article on digital archeology and how preservation of information is very difficult in the digital age.
Can you read floppies that you created merely 15 years ago? Do you even have access to a computer that has 1.44" floppy drives? What about 3.5" floppy drives? What about cassette tapes that have voice recordings? Or cassette tapes for Sinclair ZX Spectrum programs that you wrote in the 1980s merely several decades ago? What about that pre-cassette audio tape from the 60s? That was merely half a century ago?
The Device Problem
We can read the ancient medium, be it baked clay, stone or papyrus, without needing any device, merely our eyes.
That was true up to the early 20th century.
Up until that time, whatever technology we used could be easily replicated by humans if a widespread catastrophe happened. For example, telegraphs, trains, telephones, and even early airplanes, could all be manufactured in workshops having metal smelters, blacksmiths, carpenters, ...etc.
But now, we are reliant on the widespread use of complex Integrated Circuits made on silicon wafers. Manufacturing these is not easy. It is very expensive and highly specialized. Moreover, we may have reached a point where they are recursive: That is, we need CPUs, RAM and graphics chips to make production lines that make CPUs, RAM and graphics chips. Perhaps not in a total dependence (can't make them without earlier versions of themselves), but close.
Now our knowledge is stored using this technology, and it is hidden from our eyes. We need devices built using these technology in order to be able to read information such as school exercises, tax records, invoices and receipts, and pretty much anything else.
And there is also the longevity issue: if papyrus, and paper, are not durable enough to stand the test of time, what about the poor bits on a magnetic or memory medium?
Update 2014-10-28: If you are compiling a library for survival knowledge, would you make it in a digital format that requires a device using integrated circuits?