An interval is the distance between two pitches. Building an interval – positioning the second note relative to the first pitch – is a first step in creating musical meaning, a first relation in two pitches like you become aware of which water is colder than the other. The seven diatonic pitches from the tonic in the major and natural minor scales represent a variety of intervals.
Why is the scale degree 7 named differently in major and minor scales?
As we talked in chapter 1, the pitches of a scale have a hierarchical relationship. Each has its own role in characterizing the type of key. The scale degree 7 in a major scale is called a “leading tone” because it leads strongly to the tonic, a half step away. On the other hand, the “subtonic” seventh note in a minor scale is a whole step from the tonic, so it does not have the same leading effect. Play the scale degree 7 and then the tonic in the major and minor keys to compare the sound.