The Herzog August Bibliotheck in Wolfenbüttel, Germany is home to probably the first finely cataloged library that used the system we still use today. Founded in 1572 by Duke Julius of Brunswick-Wolfenbüttel, it is a very unusual library where every single one of the thousands of books is bound with bindings that are carefully organized according to subject by the scrupulous owner. The duke would almost obsessively write on each book, making sure that there was room in his system to keep expanding. For example, if a history book was labeled nr. 16, his next history book would be 16.1. This was the inspiration behind the Dewey Decimal System, as it was the first system that was well organized but flexible enough to allow for constant expansion. What a treasure that library is.