One of the most important devices in a good composer’s toolbox is counterpoint, the art of combining two or more simultaneous melodic lines. (The word comes from the Latin punctus contra punctus, meaning “note against note.”) This art has been developed over many centuries and remains prominent in the best music of today (even some popular music). Many rules have been set forth for writing successful counterpoint, and a good composer should study the subject in detail, but for present purposes we can reduce the rules to a few basic principles.
First, the individual melodies must be interesting in themselves. Neither one should sound like mere “filler” for the other. Here Pachelbel’s famous Canon in D and “Puff the Magic Dragon” are both very well-known and were written by different composers, in different styles centuries apart. Each of them is a very deserving tune in its own right, yet they “fit together” marvelously. Curiously, “One Tin Soldier,” the theme from the movie Billy Jack, would work here too!
A second principle of good counterpoint is that the melodies must be independent. They should not overlap much, certainly not for more than one consecutive pitch. In the third measure of the example, the two melodies both use the pitch D simultaneously, so they overlap under the principle of octave equivalence. That overlap, however, only lasts for one pitch. But what if “Puff the Magic Dragon” had been slightly different and descended to C-sharp in the fourth measure? In that case the two melodies would lose their independence, moving in “parallel octaves.” Since a note and its fifth are closely related (remember our post about the overtone series?), we avoid having melodies move in parallel fifths as well.
Third, the notes that sound simultaneously should either be consonant (or as most people say, “harmonious”), or else they should follow certain patterns of dissonance that are easily followed by the ear. In this case, the notes in the two melodies are mostly consonant with each other. But there are two dissonant notes: the “neighbor tone” A in the fifth measure, and the “passing tone” C-sharp in the seventh measure.
We’ll talk about some other principles of good counterpoint and look at further examples in future posts to this blog.