Pure ratio intervals on three chords generate the entire just diatonic scale

Evidence

Another important scale is the “just diatonic” scale which is made by keep­ ing the intervals that make up the major triads pure: the octave (2:1), the perfect fifth (3:2) and the major third (5:4) for triads on the tonic, domi­ nant and sub-dominant. The dominant and sub-dominant keynotes are a perfect fifth above and below the key note respectively. This produces all the notes of the major scale (any of which can be harmonized using one of these three chords). — David Howard, Jamie Angus, coustics and Psychoacoustics, 1046

Categorization

• DEFINE: Defines the just diatonic scale as built from pure major-triad intervals on tonic, dominant, and subdominant.