These I take to be normal features of any good tonal progression. I differs from the previous one only in the position of the substituted progression. The reason why the phrases include at least one substituted progression is that this is the necessary condition for the phrase to return to its starting point, the tonic. A continued series of unsubstituted dominant progressions, following a cycle of fifths, indeed, could only inexorably lead away from the original tonic. A well formed tonal phrase can therefore be defined, from the point of view of harmonic progressions, as a series of dominant progressions of which at least one is substituted.
Dominant progressions appear as lines descending from left to right.
Although it may be difficult to obtain statistics for the tonal corpus as a whole, I consider these figures to be quite typical of the common tonal practice. Example 3, from Chopin s Mazurka op. The repetition of the motive in mm. 37-39 is tonally more affirmative, in part because it is constructed on dominant progressions. The most obvious difference with respect to the examples above is that the work makes use of seven different roots, while the other examples had only four or five.