One heptatonic, or seven-note, conception of the blues scale is as a diatonic scale (a major scale) with lowered third, fifth, and seventh degrees,Smallwood, Richard (1980). "Gospel and Blues Improvisation" p. 102, Music Educators Journal, Vol. 66, No. 5. (Jan., 1980), pp. 100-104. which is equivalent to the dorian 5 scale, the second mode of the harmonic major scale. Blues practice is derived from the "conjunction of 'African scales' and the diatonic western scales".Oliver, Paul. "That Certain Feeling: Blues and Jazz... in 1890?" p. 13, Popular Music, Vol. 10, No. 1, The 1890s. (Jan., 1991), pp. 11–19. Cites Rudi Blesh.
