Contrary to Modulation 1, in which the DOMINANT seventh chords never resolve,
         Modulation 2 offers a temporary TONIC for each DOMINANT,
                   grouping the chords of the circle in binary cells, 2 by 2,
                             with weak modulations to F, Em, Dm, and, of course, strongly to C.
                                       [I⁷ IV VII⁷ IIIm VI⁷ IIm V⁷ I (C⁷ F B⁷ Em A⁷ Dm G⁷ C)]
         The second chord, F [IV] acts as a Neapolitan Sixth in the Key of Em [II of III],
                   an ANTE 1 [II] with a flat root (F),
                             whose resolution to the DOMINANT (with its F#) is delicate.

With Voice-Leading C, the resolution of the Neapolitan Sixth is awkward in Line 1,
                   with the F to F# and then to E (chords 2-4).
         Line 2 has the right resolution, with F to D# to E, and it would be preferable to leave Line 1 out.

The last 4 chords of this circle are used four times as a harmonic development motif
by Bach in the Wohltemperiertes Klavier, Volume 1, Praeludium 3 (in C# major), Bars 32-47
[VII⁷ IIIm VI⁷ IIm, III⁷ VIm II⁷ V, VI⁷ IIm V⁷ I, II⁷ Vm I⁷ IV
(B#⁷ E#m A#⁷ D#m, E#⁷ A#m D#⁷ G#, A#⁷ D#m G#⁷ C#, D#⁷ G#m C#⁷ F#)]

With Voice-Leading A, there is no problem with the resolution of the Neapolitan Sixth,
         with the F to A and then to G, in Line 1, and C to D# and then to E in Line 2, (chords 2-4).

To Modulation 3