Diatonic triads that ascend the scale degrees in a given key are also called chord functions. Furthermore, these numbers, when applied to chords (instead of single notes of a scale) are written in Roman numerals. This numbering of chords within a key helps to provide a type of musical shorthand for musicians who are interested in studying the underlying harmonic content and movement of a piece of music. This movement is typically referred to as a chord progression.

Notice that the diatonic triads in Figure 5-5 proceed as follows: G major, A minor, B minor, C major, D major, E minor, and F-sharp diminished. This pattern, which is the natural outcome of deriving chords from the G scale itself, is one that will be generated in any key. All major scale diatonic triads will progress as follows: major (I), minor (ii), minor (iii), major (IV), major (V), minor (vi), and diminished (vii).

Chord progressions can be rather simple or complex. Different kinds and eras of music hold to different standards of complexity. For instance, blues and early rock music often use merely three chords. Alternatively, modern jazz and most forms of classical music employ complex chord progressions. These chords may even extend beyond the given key and imply several keys all at the same time.

One advantage of using Roman numerals instead of alphabetical chord symbols is the fact that Roman numerals communicate relationships as opposed to absolute values. This means that they instantly communicate the underlying structure of the chord progression rather than seemingly arbitrary succession of chords. On the other hand, chord symbols are a more clear-cut, objective form of musical communication, and they are best employed when trying to actually play music (as opposed to analyzing it). You will learn more about standard chord symbols at the end of this chapter.

To get a taste of what it is like to think in Roman numerals look at Figure 5-6. Here, you will play broken triads using the Roman numerals I through vi. Included are the roman-numeral chord function symbols and the written notes. You can choose how to play these notes, but it is probably wise to use closed position 1 or some adaptation of it.

Figure 5-6.

Reading Roman numerals I, ii, iii, IV, V, and vi in G major

Uppercase Roman numerals indicate major. Lowercase Roman numerals indicate minor.

Recommended: Use the same closed position found in Figure 5-5.