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Music Theory for the 21st-Century Classroom

Robert Hutchinson

Section 30.4 Third Species Counterpoint

In third species, one writes four quarter notes to each whole note in the cantus firmus. Use the following rules.
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  1. Begin on an octave or unison. Write four quarter notes to each whole note in the cantus firmus except for the final measure.
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  2. End on a whole note on an octave or unison with the penultimate measure using one of the following formulas:
    1. If the cantus firmus is in the lower voice, the penultimate measure of the upper voice can be:
      1. \(\hat{4} \)–\(\hat{5} \)–\(\hat{6} \)–\(\hat{7} \), or
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      2. \(\hat{2} \)–\(\hat{1} \)–\(\hat{6} \)–\(\hat{7} \) (the cambiata—see 5.b. below)
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    2. If the cantus firmus is in the upper part, the penultimate measure of the lower voice is \(\hat{7} \)–\(\hat{5} \)–\(\hat{6} \)–\(\hat{7} \).
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  3. Each downbeat should be a consonance.
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  4. When crossing barlines, apply the following:
    1. “Imperfect” consonances (3rds and 6ths) can be approached in any manner.
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    2. “Perfect” consonances (unisons, 5ths, 8ves, 12ths) may only be approached in contrary motion in order to avoid direct 5ths and direct 8ves.
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    3. Do not repeat notes across barlines
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  5. Allowable dissonances:
    1. Passing tones are allowable dissonances (but never on the first beat of the measure).
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    2. The cambiata (see the melodic contour in third measure of the example below) is allowed but only with the second note of the measure as the only dissonant interval.
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  6. Direct 5ths and direct 8ves are not allowed and occur when an 8ve or 5th on a downbeat is approached through similar motion.
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