Practical or sensitive form—that the artist feels relationships, i.e. weights, measures, durations, correspondences, gravities, propulsions, and cooperates to set them in motion. The physical universe has “laws” of motion and the artist is sensitive to them. Here language—as well as paint, tones struck from the string—is a “matter” of vibrations; and form has to do with the working in structures of moving parts.
—Robert Duncan, “Notes on Poetic Form,” The Poet’s Work: 29 Masters of 20th Century Poetry on the Origins and Practice of Their Work (Houghton Mifflin Co., 1979) edited by Reginald Gibbons