I think what Gibran is trying to say is that if you “know” history, then you will learn and understand from the mistakes of those before you such that the past need not repeat itself. However, if you do not know history, then history will repeat itself because you will be making the same mistakes as those who preceded you.

I doubt that Gibran was the originator of this idea, as I’ve heard quotes similar to this thrown around as a reason to study history. However, we should bear in mind that it is often ill advisable for historians of all levels to look at history solely as a tool for the present or as something that is to be simply “known.” It is a very objectivist idea to say that there is one tangible lesson or takeaway from a particular historical event or era. Is there one definitive lesson to be learned from events like the Crusades or the Bay of Pigs? In my mind, there is not and it would be dangerous to presuppose that there is.

If you know history, then you will see that in circumstances leading to similar events were never the same. Factors that lead up to these events are almost always different and things could always go differently. There is no such thing as inevitability in history as factors are always different.

If you dont know history, you simply see the results. They see two similar events happen with similar factors and they assume "History has repeated it self!" When historians look at it, they see that the two events are in no way identical in terms of results and factors and know for a fact that the two are different events. This is why nobody can really predict the future, because if history repeating itself was really true, then predicting what will happen should be as easy as recognizing ones own palm.

If you know history, then history repeats itself. If you don't know history, it doesn't.