Some of us can remember many instances when history was changed, and was not therefore identical with the past. Often, history varies according to the country you are in at the time. For example, a town guide in Cadiz gives a very different version of the Spanish Armada from the one that is (or was) taught in English schools. Remember the Hollywood films that record how the Americans won the 1939-1945 war single handed? How about the versions of the Iraq invasion according to US sources and Middle East sources?