[B]y 1204, the only place where the entire body of Greek learning existed, still intact, was Constantinople. As a result of the crusaders' conquest, … - Isaac Asimov

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[B]y 1204, the only place where the entire body of Greek learning existed, still intact, was Constantinople. As a result of the crusaders' conquest, however, Constantinople was ruthlessly pillaged and destroyed and almost all the great treasures of ancient Greek learning were lost forever. It is because of that sack, for instance, that we have only seven plays left out of the better than one hundred written by Sophocles. The tragedy of 1204 can never be undone and for all of time, only bits and pieces of the marvelous Greek world can be known to us.