Ramsay
"The notes as they naturally arise from unity have different degrees of development, and according to the degree of development of each note is its specific levity or gravity. The three notes which form the subdominant chord have different degrees of gravity; the three which form the dominant chord have different degrees of levity. The remaining note is the center of the tonic chord -
Subdominant - F, A, C E G, B, D - dominant
[Scientific Basis and Build of Music, page 95]
See Also