The latest flap, which began at the end of July, centers on the planned selections for the 2020 edition of “The High School Songbook,” the country’s most beloved morgensang anthology. Among the hundreds of melodies being considered is an invited submission by a rapper called Isam B. titled “Ramadan in Copenhagen. ” Some critics say a song about the Muslim holiday has no place in such a quintessential symbol of Danishness.

“The High School Songbook” was used from the 19th century in Denmark’s folk high schools, popular residential institutions offering courses for people over 18 . They made morgensang a cultural staple, and the book itself a potent symbol of national identity. It is widely used in other institutions and, with 450,000 copies sold since 2006, is the country’s best-selling book.

“You could say it’s become part of the backbone of Danish democracy,” said Kristine Ringsager, an assistant professor of music anthropology at Arhus University. “The songs in it are seen as a very special treasury of what it means to be Danish.”

That definition isn’t entirely static, however. Immigration is a divisive issue here, and anxiety about it has strengthened far-right groups like the Danish People’s Party and prompted everything from a burqa ban to tortured debate over whether school cafeterias should serve pork meatballs. Yet underneath those conflicts in this once homogeneous but now ethnically diverse country is a more fundamental struggle over what it means to be Danish — and that includes what Danes sing.

There have been 18 editions of “The High School Songbook” so far, the latest published in 2006. Each edition has retained a core of classics, many of them paeans to Denmark’s landscape and seasons, but outdated songs are retired and new ones introduced. The process always generates conflict, particularly among citizens upset to see a favorite excluded. But the 19th edition, currently being selected, has produced a whole different level of controversy.