The Silmarillion was enough of a success that he went on, hesitating at first, to publish the Unfinished Tales. When he saw that Tolkien fanatics were willing to buy that he put out the 12-volume History of Middle Earth with variant scraps of various different passages so people could see how the story evolved. Thank God Bungo Baggins didn't make it to the final version. Then, I guess his gambling debts or all the hookers and blow caught up with him or something, so he had to rehash the existing material in the three new books. Hopefully it's over, finally, with this one.