In my last post, I suggested that history (and my favorite sub-field of medieval history) doesn't have a lot of practical application to the 21st century. But I lie.
Medieval history has a lot to say about the failure modes of anarchism and oligarchy, and the seductive lure to the powerful of the idea of power as private property and its pernicious affect on the common good. Also, the eagerness and effectiveness of concentrated interests in rigging the rules of society in their favor, including but not limited to upper management in large organizations finding ways to improve their personal welfare at the expense of the greater enterprise.
On a more positive note, it also demonstrates the value of the rule of law and even limited efforts to bind the government to the consent of the governed.
Also, that humans want joy. They will find it or make it, somehow. And succeed, even in a society by our standards poor and oppressed. Chaucer lived through the plague, but still he was more joyful than otherwise.