What is the generational interplay of harmony? —
When the quart (or fourth) was the tonic or fundamental, the present tonic was its quint (fifth), its most harmonic ally. Then, when it became the quart, it turned more contrasting and less harmonic. But, after all, it was still fundamental for what it was. It had to let go of its previous prime position. The quint to the present fundamental now took the place of most harmonic.
That is the progression or flow of harmony and how harmonic anchors form through a fundamental with its quint and quart. Progressive and regressive qualities balance in the present looking ahead, as well as back to where one came from. Then, a touch of the quint’s quint (the fifth of the fifth) can be hauntingly stirring.
We can see this as the generational interplay of harmony and tonalities.
To its full extent, we know this in music as the circle of fifths or quint cycle. It takes the form of a regular dodecagram, which is recognized as an expression of sacred geometry by some. Tonalibus presents this in the five-course series Harmonic and Tonality Fundamentals in its fourth module Quad Harmonic Anchors and the Quint Cycle.