When we speak about "what Music does," we often talk about "chord progressions."
The word "progression" of course, connotes "progress," or as one online dictionary defines it,
music movement, esp of a logical kind, from one note to the next (melodic progression) or from one chord to the next (harmonic progression (http://dictionary.reference.com/browse/Progression)
The metaphor of "progress" implies a direction or a narrative, a leading toward an objective. Music Theorists will speak of a underlying teleology, a deep structure in Music that propels (or impels) Music through time toward a destination.e
Today we're going to talk about the most fundamental example of progression--the motion from the tonic to the dominant, and back again. This is often known as the "tonic-dominant axis," and underpins the last several centuries of Music. Moreover, it forms the basis of the Western Tonal system, and its importance is immense.
A Gentle Reminder
Remember that we are working under the idea that "Music talks about other Music." In other words, the various musical signifiers signify other musics. Recall also that this conversation takes place whether or not we can cognitively identify its connections. Educated and sophisticated listeners are able to parse musical ideas based on their pre-existing knowledge of Music, and are therefore better able to decode these musical signifiers.
Amateur musicians (a.k.a. "unsophisticated listeners") and professionals alike should be wary of passively accepting that their existing mental vocabulary of musical ideas is enough to make them authoritative listeners. Understanding the Great Musical Conversation is a lifelong effort, and a great deal of humility and trainability is required!
Below are four examples of chord progressions. I encourage you to play each example at the keyboard, or have someone else play for you. Pay attention not only to the vertical structures (chords) but also to how each note moves from one to the next. Sing along if you can. The examples illustrate how an essential I-V-I chord progression can be extended (or prolonged) by adding harmonies to "fill in" the motion from I-V. (Reminder: In "Roman Numeral Analysis," the tonic-dominant relationship is expressed in terms of scale degrees; e.g., in C major the tonic chord [CEG] is described with 'I', and the dominant [GBD] with 'V')
Again: In each example, note how there is a motion away from the tonic (C) chord, toward the dominant (G) chord, and then returning toward the original tonic (C) chord.
Note that in the example below (C major), the chords may be reckoned in terms of names (C, G, F, etc), Roman Numerals (I, IV, V, etc) or names ("tonic" = I, "dominant" = V, etc).
Example 1: C - G - C (I - V - I)
This is the basic, elemental chord progression. The motion from C to G reflects a "motion away" from the stable, tonic chord (I), and the motion from G back to C (V-I), a return to the original chord. The root motion from G to C is understood to be the strongest root movement, a descending perfect fifth. This is heard and established everwhere, from the "circle of fifths" to the ubiquitous ii-V-I root movement in Jazz.
Example 2: C - F - G - C (I - IV - V - I)
Just as in the first example, there is a motion away from the tonic chord (I), but instead of proceeding directly to the dominant (V), a subdominant (IV) chord adds interest. The key point here is that certain chords can function as "pre-dominant" chords, whose function it is to lead toward the dominant. Upward root movement by step is understood to be a "strong" progression, although not as much as a descending perfect fifth. Note in this (and following examples), that the essential motion from I-V-I is retained, despite the appearance of embellishing chords.
Example 3: C - Am - F -G - C (I - vi - IV - V - I)
Again, the underlying I-V-I motion is here extended by adding chords to prolong the motion from C-G. Note that the progression from I-IV is accomplished by root movement by descending thirds (C-A, A-F). This type of chord root movement is often understood to be a "strong" chord progression, and is very common. That root movement also itself spells an F major sonority (F-A-C).
Example 4: C - Em - Am - F - G - C (I - iii - vi - IV - V - I)
A larger progression that begins with an ascending third, a slightly unusual event, which is followed by a descending perfect fifth, leading into the vi-IV-V-I motion heard in the preceeding example.
In the examples above, we've surveyed how an essential progression (I-V-I) can be extended or prolonged by adding chords. These chords are not added haphazardly, however, and are chosen based on established aural and written guidelines for root movement. Narratively, they add interest to the "journey" (or progression) away from the tonic chord, while propelling the music toward its musical destination.
The metaphor of "progress" or "progression" serves to underscore the notion that chords "travel" from a source to a destination, and back again--this is the underlying, fundamental structure in Music. We'll talk more about this in the next post. In the mean time, keep playing and listening to these examples!