I once got to visit the library at Trinity College in Dublin. It houses manuscripts dating back to the 16th century, including some exquisite hand-written Celtic books. The library proper has bookshelves two stories high. I stood between the long rows of books, gazing at the hundreds and hundreds of leather spines, and found myself grinning like an idiot. I was happy with the thought that so much human knowledge is put forth in such a way that other humans can gain the same knowledge. I was grinning over the limitless possibilities.
For the digital age, The Universal Digital Library and its Million Book Collection is a good go. It is a work in progress, but you just may find the one gem you were looking for.