The predominance of quest stories about parties of men and elves and dwarves fighting Dark Lords is not just due to Tolkien’s influence—or rather, that influence is due to a chord the great author struck in the common spirit of the times. It answer a deep seated need to find quests, something worth fighting for, in a questless world.
John C. Wright
What Is the Future of the Future?
Success comes most swiftly and completely not to the greatest or perhaps even to the ablest men, but to those whose gifts are most completely in harmony with the taste of their times.
Putting these pieces together, I have a great way to predict the general success of different forms of fiction. As the Great War approaches yet again and the Hero Generation comes of age to fight and die in it, we should expect that stories about bands of brothers will predominate. Similarly, we should expect the next generation of media to be countercultural, like in the 70s.
Therefore, a miser like me would do well to find free books from the 1940s, 1860s, 1770s, and so on whenever a fourth turning was happening.