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This is the only ancient account that explicitly states what happened to the library. Some historians dismiss this account as motivated by bias against Caesar. Whatever motivated Plutarch, the account establishes that the library no longer existed by AD 100, when he was writing.<ref>Plutarch visited Alexandria, so he would certainly have known if the library still existed in his time.</ref> [[Edward Gibbon]] wrote that the library was destroyed by Christian rioters in AD 391. This claim has been repeated in numerous accounts by anti-Christian writers, but it is not supported by any source older than Gibbon.
The loss of the Library, which contained the original (and sometimes ''only'') copies of most of the ancient world's greatest works of literature, resulted in the decimation of ancient literature, and accounts for the modern paucity of ancient materials. Scholars estimate that historians now have only 1/10th of 1 percent of the ancient world's original source material to rely upon, as an almost exclusive result of the library's destruction. As an example, among the material lost in the library was a first-hand account of the life of [[Alexander the Great]], written by his general and boyhood friend, [[Ptolemy]]. Historians know of the book's existence by a citation to it in secondary sources.