Counterpoint Study 2: Motion

Counterpoint Study Lesson 2: Motion

Some rules in counterpoint consider the motion of the notes. Motion is defined as how the notes are arranged horizontally. In counterpoint, the main melody is called as cantus firmus (or CF), whereas its counterpoint is simply called counter point (or CP). The notes arrangement between CF and CP form motion. These motions also referred to as contrapuntal motion. There are four basic type of contrapuntal motion:

1. Parallel, characterized by motion which has the same interval (CF and CP move within the same intervals). 
2. Similar, characterized by motion which has the same direction but has different interval (CF and CP move in the same direction but within different intervals).
3. Contrary, characterized by different direction between CF and CP.
4. Oblique, characterized by no change in pitch (in one melodic line), whereas the other goes up or down.

Below is the example of each contrapuntal motions, along with their respective intervals.

Analysis: Assume that clef G is the CF and clef F is the CP. On the first bar, the interval doesn't change, thus its a parallel motion. On the second bar, CF's and CP's melodic lines go on the same direction (down) but the intervals change, hence its a similar motion. On the next bar, CF's melodic lines go up whereas CP's melodic lines go down, hence its a contrary motion. Last, on the fourth bar, CF's melodic lines are on the same pitch whereas CP's melodic lines go down, hence its an oblique motion.