JRR Tolkien started writing a sequel to the Lord of the Rings.
I did begin a story placed about 100 years after the Downfall [of Sauron], but it proved both sinister and depressing. Since we are dealing with Men it is inevitable that we should be concerned with the most regrettable feature of their nature: their quick satiety with good. So that the people of Gondor in times of peace, justice and prosperity, would become discontented and restless – while the dynasts descended from Aragorn would become just kings and governors – like Denethor or worse. I found that even so early there was an outcrop of revolutionary plots, about a centre of secret Satanistic religion; while Gondorian boys were playing at being Orcs and going round doing damage. I could have written a ‘thriller’ about the plot and its discovery and overthrow – but it would be just that. Not worth doing.
I think that says as much about our World as Middle Earth. No moment of triumph ever lasts. It’s a second law of thermodynamics for societies.