Actually, I've given up on trying to associate this with any one originator or author. There are many that assign this to the writings of E.H. Carr, but I have not been able to find it. You can find this quote and variations of it attributed to Goering, Churchill, Stalin, Napoleon, and on-and-on.
Mostly, I find it referred to as a truism or aphorism.
http://forum.quoteland.com/eve/forums/a ... 7311944162
…only the future can provide the key to the interpretation of the past; and it is only in this sense that we can speak of an ultimate objectivity in history. It is at once the justification and the explanation of history that the past throws light on the future and the future throws light on the past.
~ E. H. Carr
But, just after providing this quotation, the author states:
At first, Carr’s claim appears little better than those trite aphorisms: ‘history is written by the victors’ and ‘save us from the condescension of the historians’.”
~ Stephen T. Casper athttp://www.dictionaryofneurology.com/20 ... vidal.html