The past after all is only another name for someone else's present.

In writing history, to catch the feeling as well as the "truth" of other times, it is of utmost importance, I believe, to convey the sense that things need not have happened as they did. Life in other times past was never on a track, any more than it is now or ever will be. The past after all is only another name for someone else's present. How would things turn out? They knew no better than we know how things will turn out for us.

David McCullough, Brave Companions