“the aim of studying history is not to forget its lessons when occasion arises for its practical application, or to decide that the present situation is different after all, and that therefore its old eternal truths are no longer applicable; no, the purpose of studying history is precisely its lesson for the present. The man who cannot do this must not conceive of himself as a political leader; in reality he is a shallow, though usually very conceited, fool, and no amount of good will can excuse his practical incapacity.”
You may hate me for this one, and I did hesitate before posting it, because the source is Adolf Hitler in Mein Kampf. But it remains true even if the person who said it was evil.