Bruno Nettl (1989, p. 162-163) proposes that Blackfoot music is an "emblem of the heroic and the difficult in Blackfoot life", with performance practices that strongly distinguish music from the rest of life. Singing is strongly distinguished from speech and many songs contain no words, and those with texts often describe important parts of myths in a succinct manner. Music is associated closely with warfare and most singing is done by men and much by community leaders. "The acquisition of songs as associated with difficult feats—learned in visions brought about through self-denial and torture, required to be learned quickly, sung with the expenditure of great energy, sung in a difficult vocal style—all of this puts songs in the category of the heroic and the difficult." (Nettl 1989, p. 162-163)