The Danish sociologist Benedikte Brincker observes that the perception of Nielsen and his music in his home country is rather different from his international appreciation. His interest and background in folk music had special resonance for Danes, and this was intensified during the nationalistic movements of the 1930s and during World War II, when singing was an important basis for the Danes to distinguish themselves from their German enemies. Nielsen's songs retain an important place in Danish culture and education. The musicologist Niels Krabbe describes the popular image of Nielsen in Denmark as being like "the ugly duckling syndrome" – a reference to the tale of the Danish writer Hans Christian Andersen – whereby "a poor boy ... passing through adversity and frugality ... marches into Copenhagen and ... comes to conquer the position as the uncrowned King". Thus while outside Denmark Nielsen is largely thought of as the composer of orchestral music and the opera "Maskarade", in his own country he is more of a national symbol. These two sides were officially brought together in Denmark in 2006 when the Ministry of Culture issued a list of the twelve greatest Danish musical works, which included three by Nielsen – "Maskarade", the Fourth Symphony, and a pair of his Danish songs. Krabbe asks the rhetorical question: "Can 'the national' in Nielsen be demonstrated in the music in the form of particular themes, harmonies, sounds, forms, etc., or is it a pure construct of reception history?"