Content and substance (Gehalt) in music is the difficult theme of this volume. The central questions are: in what manner is music more than immanence, structure and autonomous meaning, and to what degree do "extramusical" ideas and conceptions shape the work so that more appears to be in it than music alone. This theme is above all relevant for contemporary music of the 21st century, as ever more composers are interested both in cultural discourse and in a content-orientation for their music. This volume presents essays by twelve composers who were invited to ponder the relationship between musical structure and the substance of music in light of their own musical practices.