(Fr. conduite des voix; Ger. Stimmführung; It. condotta delle voci).
That aspect of counterpoint and polyphony which recognizes each part as an individual line (or ‘voice’), not merely as an element of the resultant harmony; each line must therefore have a melodic shape as well as a rhythmic life of its own. In discussions of part-writing a distinction is made between linear or conjunct motion and movement by leap (i.e. by a 3rd or greater) in a single part, and between various types of relative motion between two or more parts: similar motion, two or more parts moving simultaneously in the same direction; parallel motion, two or more parts moving in the same direction and at the distance of the same interval or intervals; oblique motion, one part moving while another part remains stationary; and contrary motion, two parts moving in opposite directions. In good part-writing each part is shaped to a recognizable contour (such as an ascending or descending line, or an arc) having an identity in the polyphonic fabric of a composition or passage. Conjunct motion is generally preferred to movement by leap in all parts except the bass; similar motion among all the parts (except in two-part writing), hidden (covered) 5ths or octaves between the outer parts and consecutive (parallel) 5ths or octaves between any parts are usually avoided.
WILLIAM DRABKIN