A lost work is a ocument or literary work produced some time in the past of which no surviving copies are known to exist. Works may be lost to history either through the destruction of the original manuscript, or through the non-survival of any copies of the work. Deliberate destruction of works may be termed literary crime or literary vandalism. In some cases fragments may survive, either found by archaeology, or sometimes reused as bookbinding materials, or because they are quoted in other works. The most famous recent example of an original or early manuscript is the discovery of the Archimedes palimpsest hidden in a much later prayer book. Most of the missing works are described by works or compilations which fortunately have survived, such as the Naturalis Historia of Pliny the Elder or the De Architectura by Vitruvius. Often authors wanted to destroy their own works, or instructed others to do so after their deaths, and we are fortunate that such action was not taken in several well-known cases, such as Virgil's Aeneid saved by Augustus and Kafka's novels saved by Max Brod. Many works were apparently lost when the Library at Alexandria was burnt down in the Roman period, or perhaps later. Before the era of printing, manuscripts were handwritten, and so few copies existed, helping to explain why so much has been lost. Works which are not referred to by others must, of course, remain unknown and totally forgotten.