Cadential Structure: [I-IV-V-I] - Lester Allyson Knibbs, Ph.D.

[ I - IV - V - I ]: Basic Analysis of Chorale Harmonization (Summary)

Example 215.1 is Bach's harmonization with my cadential structure analysis. Row (a) is a simple analysis indicating the structure of each phrase. The opening two phrases are a binary statement, and the last two phrases recapitulate that idea. In between, we have some ambiguity. Row (b) indicates a recurrent idea which I suspect is the key to the middle section. Row (c) presents my (tentative) conclusion that the middle section begins a prolongation of the tonic which continues into the penultimate phrase. This conclusion is based on the recurrent pattern of {I>V>vi>IV>I} which prolongs the tonic in the first and fifth phrases. This pattern also extends from the end of the third phrase to the beginning of the fifth phrase. This pattern suggests that the fourth phrase, instead of being an inside-out prolongation of the tonic, is an elaborated motion from the submediant to the subdominant. The strong root-position tonic in the middle of this phrase - accented in the text, as well (see #17 in C.P.E. Bach's 185 Four-Part Chorales for the text) - goes against that interpretation. Frankly, I love the contradiction. Both analyses are true; the ambiguity is real: this is both (1) an inside-out prolongation of the tonic and (2) a motion from the submediant to the subdominant using the tonic as a connecting harmony. It is important to notice that the harmonic structures holding this composition together cut across phrase boundaries. In symphonic works, such harmonic structures cut across sectional divisions. (And in some symphonies of Gustav Mahler, harmonic structures transcend the divisions between movements.)

Example 215.1

This form of analysis helps us to grasp the larger structures of musical compositions. I am indebted to the concepts of Heinrich Schenker and Felix Salzer, as presented in the latter's Structural Hearing, but I am proposing a significant difference. The [I-IV-V-I] pattern is central to this form of analysis. For example, Liszt's Etude in D-flat (Un Sospiro) seems to modulate in a series of major thirds from D-flat major to A major to F major and back to D-flat major. This pattern is real and might be emphasized in Salzer's form of analysis, but the underlying cadential structure holding this composition together is strong and rather conventional, and the modulation in major thirds turns out to be a beautiful illusion. Another difference is that cadential structure is harmonic, not contrapuntal, focusing on the bass-line, whereas Schenker analysis deals with multiple lines. I am also indebted to Arnold Schoenberg's concepts as presented in Structural Functions of Harmony.

Every musical composition is a varied repetition of the music that came before it, and every musical composition in the tonal period consists of varied repetitions of the [I-IV-V-I] pattern. Theme-and-variations on a grand historic scale.

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