From a famous passage in George Orwell's novel 1984:
"He who controls the past, controls the future; and he who controls the present, controls the past."
This is the motto of the Ministry of Information, spoken by O'Brien. Essentially, those who are in power write the history books. Our view of history--how we are told it happened--shapes our response to that history, and hense our future. There is no objective past, because there is no objective human being. We are subject to the winners' gloating.
However, some are more objective than others. Certainly the "history" of mythology is less objective than that of modern historians. Or is it? It only takes one crackpot to start the Holocaust deniers and Confederate apologists ala John Ashcroft. For years, our films were filled with disgusting stereotypes of African slaves, Native Americans, Asians, Latinos, women, and the poor. Thankfully, those who have been stereotyped have begun to fight back by writing their own histories.
"He who controls the past, controls the future; and he who controls the present, controls the past."