The music of Lou Harrison is music of melody. There are lots of things to be said about his experimental techniques and research, especially in his use of found or casual objects as instruments, and his use of non-Western and mathematical sources for tonal and rhythmic content. Harrison also worked closely with the movers and shakers of American 20th Century music (especially Charles Ives), and explored the powers of improvisation. But his music is not about the experimentation, or the anxiety of influence. It is music of rich, bright innocence, which most often comes out as melody.
The ductia, we can say with certainty, is a medieval dance. What sort of a dance it was we cannot say, because none (or no work given as a ductia) exists. There remains only a description of the dance, from Johannes de Grocheio (c. 1300 CE), which compares the ductia to the estampie, and which gives the following about its character:
The ductia is a melody that is light and brisk in its ascents and descents, and which is sung in carole by young men and girls, like the French song Chi encore querez amoretes. It influences the hearts of young girls and men and draws them from vanity, and is said to have power against that passion which is called love or ‘eros’.
Harrison’s ductia may or may not have something to do with this description. But it is a beautiful introduction to the sound and character of this fine and generous American composer.