Species II: Two notes against one
A. Melodic line: continuous half-note motion. The penultimate tone of a phrase may be a whole note; the final tone must be a whole note (with fermata as in CF).
1.The same principles of linear motion and melodic gravity as those of Species I apply, but still more care must be taken to produce a smooth yet purposeful line. The downward leap of an octave may be used in a lower CP, within a measure. The downward leap of a minor sixth may be used in an upper CP, within a measure.
2. a. No repetition of tones in immediate succession.
b. The same pitch must not occur more than twice in succession on consecutive strong halfs (halfs simultaneous with the sounding of the CF note); and that only if the CF tone changes. To use the same note of CP against the same note of the CF would be to emphasize the vertical aspect of the two melodies and "lock in" the independent motion.
c. No use of "sequential figures" is allowed. The style does not really rely on motivic generation, and this kind of development is seens as impeding the purity of the line. However, some apparently sequential figures are not heard as such if they happen to start fom the weak half of the measure. The reason is that the change of CF note would be with the second CP note of the apparent sequence.
d. No more than three successive measures may contain skips, and no more than one such succession of measures in each phrase is allowed.
e. Skips of a fourth within the measure should be approached or continued from within the fourth; when the fourth is descending, both approach and departure must be within the fourth.
1. Half-notes which coincide temporally with tones of the CF are called "strong halfs." They must be consonant with the CF. The second half-note of each pair is called the "weak half." It may be consonant with the tone of the CF.
2. The weak half may also be dissonant with the tone of the CF, but it then must be a passing tone dissonance only. That is, it must be approached by step and left by step, continuing in the same direction. In other words, it fills the interval of a third (major or minor) between two strong halfs (ordinarily, in Species V and in two-part pieces, the weak half can never be dissonant).
3. When the CP produces the interval succession against the CF of 6-5 or 5-6, it must always be continued in stepwise motion, in either direction (as a general rule, one should never leap to or from a dissonance: exceptions involve double neighbor figures in Species III and escape tones in Species IV).
1. Unisons are to be used only at the beginnings and ends of phrases, or on weak halves.
2. Parallel octaves and fifths are prohibited:
. a. Between immediately successive sonorities; i.e., between a weak half and the immediately following half.
b. Between successive strong halfs, unless the second octave or fifth is approached by contrary motion and left continuing in the same direction. There should not be more than two such octaves or fifths on successive strong halfs.
c. Between successive weak halfs, unless the weak-half fifths or octaves are approached from opposite directions.
3. In measures containing a sixth and a perfect fifth (6-5 and 5-6 measures), the second tone must continue on stepwise.
Note: Species II measures may be grouped into two categories, the second subdivided:
a. The weak half is a dissonant passing tone.
b. The two halfs are both consonant with the CF.
1) They are also consonant one with the other (third, fifth, sixth, octave melodic skip).
2) They are dissonant one with the other: perfect fourth skip or step.
In this species the pairs of half notes will be consonant with one another and/or with the CF, or they will be mutually dissonant or mutually consonant. Remember, that in the real style the half-note positions are always consonant with the CF.