Josephfarrar wrote: ↑
Wed Jul 31, 2013 8:29 am
What i do not understand is that what happens when you move from the 1st note of say the major scale in C to the 4th (G)? Is that not movement from a perfect consonance to a dissonant one? Because of course melodies can utilize all notes from within a scale how can the rules only be applied to perfect and imperfect?
I think perhaps this is not talking about horizontal movement.. But i can't see how else it could apply.
If the melody is for example. D F E F G F A G F E D, or in scale degrees (Dorian mode), 1 3 2 1 4 3 5 4 3 2 1. The seconds and the 4th should be classed as dissonant intervals and should not be used (Or rather the rules can't be applied to this movement) according to Fux's rules. But this melody is taken from a cantus firmus and so is obviously used within this setting.
What is it that i am failing to understand about the rules?
Joe is confusing melodic motion, in which a single voice moves by intervals, with harmonic relationship, in which intervals are created between two or more voices sounding simultaneously. When one of the voices moves, it must take into account the interval to be produced between it and the other voices or voices. In beginning exercises, the first voice, called the cantus firmus, is given in a fixed form, and is NOT subject to these rules, and it is the second melody (which accompanies this first melody and which the student is supposed to compose) which must obey the rules.
The Dorian melody quoted by Joe is similar to the Dorian cantus firmus given by Fux. It contains, by itself, only melodic intervals. A second melody is required in order to produce harmonic intervals by harmonizing with this first one, and the student is supposed to compose this second melody. What the first melody is doing is not subject to the rules; it has already been composed. The job is to stack another melody on top of the cantus firmus (or below it), to create a note-against-note counterpoint, and this second voice is the one which must follow the rules, using the three motions appropriately according to what interval will be created between the notes which the two voices simultaneously sing together at each step. The interval used in the melodic motion of each individual voice is a different issue; there what's important is the type of motion, contrary, parallel or oblique, and whether the interval by which the counterpoint moves in relationship to itself, is a perfect or imperfect interval, is not relevant. (Note that there is no oblique motion in the following counterpoint, as this would require one voice to repeat a note. Oblique motion usually occurs with one voice moving in faster notes than the other.) It is whether the interval produced by the simultaneous sounding of the two voices is perfect or imperfect that is relevant to the direction of movement made to get to this point. There are, in this counterpoint, four perfect intervals and seven imperfect intervals.
D4 A3 C4 D4 E4 F4 E4 B3 D4 C#4 D4 (added melody, i.e. counterpoint)
D3 F3 E3 F3 G3 F3 A3 G3 F3 E3 - D3 (cantus firmus)
As the counterpoint moves to each new intervalic relationship with the cantus firmus, it must do so by the correct movement. Thus at the sixth note, there is an octave F4 above the cantus firmus's F3, and this is approached in contrary motion. However, it is the second voice which must choose this motion in relationship to the pre-existing shape of the cantus firmus, because the cantus firmus has already been composed.