Its first 16 bars go like this:
Em Bm C G B C Eb G Cm G Ab Eb G Ab Eb G
Notice how similar measures 1-6 are to 9-14: all that's changed is that we've moved down a major third and turned the minor in bar 2 into a major. And measures 7-8 are exactly the same, no transposition, as 15-16. Separately with the exception of measures 7-8, we can see the roots of these chords aligning up the diagonal:
E B C G B C * * C G Ab Eb G Ab Eb G
almost suggesting there is a 3-measure grouping on top of the more easily felt 4.
And then the whole 16-pattern repeats itself down a major third, and then down another.