GENERALIZATION OF HARMONIC PROGRESSION

All harmonic progressions, regardless of style, adhere to the following guidelines. Whether writing in an pantonal, tonal, or modal context, if a composer desires harmonic movement, these aspects warrant careful consideration.

1. Roots change between adjacent chords;
   
2. The relative strength of chord roots are often unequal, with chords that possess strong roots acting as harmonic goals or pillars;
   
3. Functional categories of chords are created through maximal similarity (i.e., common tones);
   
4. Voice-leading governs the coherence of a musical surface.