But, returning to the chord pattern of I-IV-V, the simple harmonic motion between I and IV (for example, G and C) is a common element in American gospel music, which is one of the fundamental bases from which American musical styles evolved. Insert the V chord and you seek the tonic (another way of referring to I) from a fourth below, and have the I-IV-V which is the primary progression of the 12 bar blues, most 50’s and 60’s rock and roll, and American folk and country. You can modify the way in which you use these three chords and obtain new expressions, e.g., I to V, then down to IV, then back to V before resolution. Chord progressions are simply harmonic routes leading the music towards or away from a particular tonic chord (the key center) that we can choose to traverse to suit our own artistic direction, with a particular style of music offering its template of chords within which to operate---or to depart from when a new style is created. "A song has a few rights, the same as other ordinary citizens. If it feels like walking along the left hand side of the street, passing the door of physiology or sitting on the curb, why not let it? If it feels like kicking over an ashcan, a poet's castle, or the prosodic law, will you stop it?" [A quote from American composer Charles Ives]
So, as The Preacher claimed so long ago, is there nothing new under the sun and all that will be done has been done before? I don’t believe so. For travelling a well-known set of paths, chord progressions, we can create new sequences of notes dancing in, out and among these paths---the melody: Now there’s the crux of the biscuit (using Zappa’s inscrutable but oddly appropriate phrase) for me! A song using the I-IV-V chords can completely transcend the common routes and cause you to forget you have ever heard it before, for example, the great gospel song (there is a lesson here also, i.e., why do the gospel songs offered in recent years lack melodic soul---when the host culture lacks soul is it possible to express such a melody?), How Great Thou Art. If you place the song in the key of C, it begins with the I chord, C, but the melody immediately catches your attention by repeating a G note three times (“O Lord my”) and dropping to an E note (“God”), possibly because this represents kind of a reverse arpeggio on the triad of which the C chord is composed (C note + E note + G note is the normal ordering of a C chord). …and so on, the melody of this song just moving me, making me actually feel the awesome wonder spoken of by the lyrics from the first time I heard it in a Baptist church a half century ago.
I don’t think about music theory when I’m listening to a song (I’m referring to the musical composition rather than the lyrical composition here, though the two are related ideally, the music of the composition helping others to get to the same place we are in the story we are telling, the poem we are expressing, with the lyrics) and I normally rely on intuition when I’m writing a song. A portion of a chord progression or melody might come to me on its own (from my muse, or Moose as we jokingly referenced, grin) and only afterwards might I consider music theory in order to pursue elaboration of this core (if the Moose is stingy at that point). I’ve found you can kick the Moose in the ass by running through music theory scales or chord progressions and letting Him (His Mooseness) tell you what has potential (by what you feel intuitively on hearing those, often in the context of the lyrics mood). Chas and I used that technique in composing many of the songs on the Out of Time and Just One More Time albums (after Chas complained about our use of I-IV-VII on a couple of songs, e.g., Shattered Apple Pie, Blind Man’s Vision---he feared falling into that formulaic chording pattern…though John Cougar, among others, made a career out it).
A good melody is what draws me in…and to some degree the judgment of what is a good melody is a matter of personal experience, i.e., what makes the particular listener feel something notable.