Diatonic scale are major scales (those with a major third/triad: Ionian, Lydian, and Mixolydian), three are minor (those with a minor third/triad: Dorian, Phrygian, and Aeolian). To these may be added the seventh diatonic scale, with a diminished fifth above the reference note, the Locrian scale. These could be transposed not only to include one flat in the signature (as described by Glarean), but to all twelve notes of the chromatic scale, resulting in a total of eighty-four diatonic scales. The modern musical keyboard originated as a diatonic keyboard with only white keys. The black keys were progressively added for several purposes:
Blues scale G, B. The latter is the hexatonic scale (top). The heptatonic, or seven-note, conception of the blues scale is as a diatonic scale (a major scale) with lowered third, fifth, and seventh degrees Blues practice is derived from the "conjunction of 'African scales' and the diatonic western scales". \override Score.TimeSignature #'stencil = ##f \relative c' { </score> Steven Smith argues that, "to assign blue notes to a 'blues scale' is a momentous mistake, then, after all, unless we alter the meaning of 'scale'". An essentially nine-note blues scale is defined by Benward and Saker as a chromatic variation of the