Exercises in strict voice-leading, or species counterpoint, begin with a single, well formed musical line called the cantus firmus (fixed voice, or fixed melody; pl. cantus firmi). Cantus firmus composition gives us the opportunity to engage the following fundamental musical traits:
The “rules” of counterpoint are compiled from the important writings and treatises of the eighteenth century, most notably Johann Joseph Fux. As with all historical studies, especially those that are spread across a continent over decades, there are inconsistencies between systems and styles. We will be looking at a simplified version of contrapuntal writing to focus our thoughts on melodic interaction, however I urge you to complete a full study of counterpoint in order to properly explore this critical facet of music. That being said, our discussion of this topic will be relatively brief, so do your best to absorb the method and overall importance of good counterpoint (voice-leading).
We will consider three types of melodic intervals:
We use the terms stepwise, skip, and leap exclusively to describe melodic intervals; do not use these terms to describe harmonic intervals. For harmonic intervals, we use the types of motion (e.g. parallel, similar, etc.) combined with the size of the intervals (e.g. parallel 3rds, etc.)
In first species counterpoint, we begin with a cantus firmus (new or existing) and compose a single new line—called the counterpoint—above or below the cantus firmus. That new line contains one note for every note in the cantus: both the cantus firmus and the counterpoint will be all whole notes. Thus, first species is sometimes called one-against-one or 1:1 counterpoint.