Fyodor Lopuokhov called Swan Lake a `` national ballet '' because the swans come from Russian sources , while many of the movements of the corps de ballet came from Slavonic ring-dances . The Russian ballet patriarch Fyodor Lopukhov has called Swan Lake a `` national ballet '' because of its swans , who originate from Russian lyrically romantic sources , while many of the movements of the corps de ballet originated from Slavonic ring-dances .