In 1984, George Orwell's protagonist Winston Smith has a nice job at the Ministry of Truth vaporizing inconvenient documents by shoving them into a receptacle at his desk. The receptacle is called a Memory Hole. Once the documents are ashes, history has changed.
Something similar recently happened in Sweden. It seems that one Swedish schoolbook, a textbook for religious history classes, contained two images of the Prophet Mohammed. In the wake of the torrent of violence and vitriolic hatred pouring out of the Islamic world following the publication of the Danish cartoons, Sweden has decided to pull the textbooks from the classrooms, and the publisher has taken them out of circulation.
A gesture of reasonable conciliation, you might think -- cowardly, but within the bounds of reasonability. Except that the two depictions of Mohammed weren't scurrilous caricatures from the pen of some insensitive Western cartoonist; they were both from Islamic manuscripts of the 13th and 14th centuries. They are a legitimate part of the historical record; when the book was written, the Swedes probably thought they were being sensitive by depicting Mohammed with historical Islamic artwork.
But historical truth doesn't matter to the imams. If you don't like something from the past, suppress it. Just shove it down the Memory Hole, and trust the suicidal West to forget the whole thing ever happened.