Contrary motion
From Free net encyclopedia
In music theory, contrary motion is the general movement of two melodic lines or pitches in opposite directions. For example, in one melodic line a note moving to another of a higher pitch, a second line in contrary motion would have this note moving to another of a lower pitch at the same time.
Contrary motion is contrasted with similar motion, which is movement of two melodic lines in the same direction.
The concept of contrary motion is important in the analysis of musical themes. To create a variation of a certain theme, one technique is to subject the theme to make it move in contrary motion to the original.