Goal Oriented Root Relations: Melodic perfect fifths and major thirds are strongly goal oriented. So are the chord progressions based on these intervals.

If the melodic interval between the roots of two chords is a perfect fifth or major third down, movement is toward the root of the interval. This produces the effect of harmonic closure.

If the melodic interval between the roots of two chords is a perfect fifth or major third up, movement is away the root of the interval. This produces the effect of movement away from closure.

Harmonic closure is strongest in fifth relations.