Mangs left a lasting impression on young Morthenson, who would later refer to him in an obituary as one of the most important contemporary music critics in Sweden.
[7] Fueled by his belief that traditional compositional techniques had been exhausted and future composers would need to create something brand new in order to progress their art,[9] Morthenson's main focus and contribution in the 60s was his non-figurative music.
[8] Beginning in 1962 with Coloratura III (1962-63), Morthenson's non-figurative period was characterized by the avoidance of all traditional musical gestures, tools, and goals, resulting in a focus on timbre and density of sound, using these as compositional building blocks.
As the piece progresses, it becomes increasingly more intense and modernistic, representing Morthenson's belief that folk and avant-garde music probably cannot exist simultaneously for much longer.
A non-exhaustive list of these pieces includes Decadenze I, Farewell, Senza (1970), Collosus (1970), Labor (1971), and Alla Marcia (1974), criticizing church music, requiems, string repertoire, orchestral works, virtuoso solos, and militaristic genres, respectively.
[10] In an interview with Björn Gottstein in February 2008, Morthenson reflected on his career, stating: “I have worked with three major aspects of music in my life.