In the first of these, at the top of the diagram, the musical triad (with its lowest note, the tonic, C, replicating an octave higher) is matched to a compound figure comprising a number of shapes: a large circle (representing the tonic, the low C), a much smaller triangle centered within that circle (representing the chord’s next note up, the mediant, E), a still smaller square (the dominant, G), and finally, within that square, a second, much smaller circle, representing the upper-octave replication of the tonic, C. Here, the relative sizes of the shapes are determined by the relative pitch heights of the notes they represent: lower notes get larger shapes. The next two figures within the diagram show the two “inversions” of the musical triad: here, the mediant (E) and then the dominant (G) become the lowest sounding note (instead of the tonic note). The geometrical shapes that represent those notes (first a triangle for E, then a square for G) then undergo an analogous “inversion” in space, as their relative positions and sizes change to reflect the changes in the relative pitch heights of the notes.