If we have learned from the past then over the centuries we ought to have accumulated so much knowledge that things like war, poverty, injustice and immorality ought not to exist. Of course, we've still got a long way to go in this respect. You may also have heard that everything repeats itself, so if we study the past, we can be sure to know something of the future. I don't hold to this view either. To insist that the study of the past will reveal something of the future is a nice idea, but what I really want to know about is the present.
History can, on the other hand, reveal all that is the present.
I can only hope to answer by telling you why I study history. I first began to appreciate the study of history as an undergraduate studying political philosophy at Boston University. But what I soon discovered was that my lack of understanding of history, i.e. the actual historical context in which these writers conceived and executed their theoretical work, made my understanding of their philosophy one-sided. Sure, I knew what they had to say about liberty, or the proletariat, or monarchy or the franchise. Ideas are not akin to balloons hanging from the ceiling of Clio's den, waiting to be retrieved by a Marx, a Mill or a Plato.