Diagonaalmuziek
The origin of Diagonaalmuziek voor strijkers ['Diagonal music for strings'] dates back to the 1950s, a period in which I, preoccupied with the question of tonality and the role of the tone centre, experimented with what I would call the 'diagonal-idea'.
In brief, this amounts to a procedure of arranging the twelve tones of the equal temperament according to their position on the circle of fifths instead of their being arranged according to series as in the sense of serialism.