In second-species counterpoint, the counterpoint line moves in half notes against a cantus firmus in whole notes. This 2:1 rhythmic ratio leads to two new “fundamental musical problems” – one metric and one harmonic:
The introduction of harmonic dissonance into second species adds to the variety of the musical texture. However, it brings a tension that must be balanced with consonance to promote a cohesive tonal progression, and it requires careful attention in order to maintain smoothness in and out of the dissonance.
If we consider first-species counterpart the most “basic” interaction between two melodies, adding this second note against a harmony also provides an opportunity to begin discussing the shapes and patterns that composers use to embellish a simple melody.
Use the following examples of second-species (2:1) counterpoint to develop guidelines for writing in this style. Each of the following examples is in the major mode and has the counterpoint above the cantus firmus, but again, be aware that these two characteristics are not indicative of all counterpoint; we are using a simplified structure as our introduction.
As you develop your rules for second-species counterpoint, look only at the counterpoint (CP) line; the cantus firmus (CF) was provided, so the counterpoint line was written by following the stylistic rules.
Generally, your rules should be divided into three categories:
Instead of the 1:1 ratio in first species between pitches of the cantus firmus and counterpoint, second species has a 2:1 ratio–most often notated as two half notes for every one whole note. This creates a pattern of strong and weak beats and consequently a series of rules that are defined by the contrapuntal place in the measure.
Second species counterpoint also allows for a key element that is not an option in first species: dissonance. Strong beats must still only use consonances. Weak beats may use dissonance, although there are many restrictions.
For our studies, we will start the counterpoint with a rest on the strong beat followed by a perfect interval on the weak beat. From that point forward, you will follow these harmonic rules:
Starting and Ending Intervals:
passing motion (P): motion approached by step and left by step in the same direction
neighbor motion (N): motion approached by step and left by step in the opposite direction
appoggiatura (APP): motion approached by leap and left by step in the opposite direction