Original: While this definition encompasses many scales and modes such as Dorian mode and the Phrygian mode , the term in its stricter sense is usually limited to the natural minor , harmonic minor , and melodic minor scales , described below , which are in most common use in Western classical music ( see major and minor ) .
Simplified: They thought that a whole step between these two scale degrees was better for smooth melody writing , so they used the subtonic seventh , or raised the sixth scale degree .