The Idea of Nationalism shows its age somewhat as chapter seven goes forward.
Kohn spends a considerable amount of space in this chapter writing about the Prussian experience with nationalism. That experience being that all of the ingredients were present, but instead of being turned toward fostering a strong universal feeling or idea, they were turned to gaining power for the ruling house of Hohenzollern.
However, since 1947, Prussia has been officially abolished as a country. Kohn published this book in 1944. Quite honestly, though, this emphasis on a country that is no more is really the only thing that's reminded me of the book's age so far. I've been perfectly fine chalking up other smaller ticks to the eccentricities of any good historian.
Pulling things back from Prussia, Kohn gets into it only as a sub-section of his general study of German nationalism. The folklore has yet to really make a star appearance, as promised by the chapter's title, but at this point I think it might have just been Kohn's highlighting the sexiest part of this chapter. After all, folklore was big in the 1940s, as it had been in the eighteenth and nineteenth centuries.
Nonetheless, it's interesting to know that German nationalism was inspired by English, French, and American nationalism though it also aimed to undercut them. To those Germans concerned with such matters, nationalism that came from civilization was of a lesser order than that which came from the nation itself. In line with Rousseau's idea of the earliest humanity being the purest (as it was free from civilization's taint), the nation's character was understood to be embodied in the practices and traditions of the common people.
With eighty-two pages left in this chapter, it's entirely possible that a more folklore-centric discussion lurks ahead, but that seems rather doubtful. Kohn will likely instead continue forward in time, detailing all of the steps that Germany took to arrive at its contemporary state.