Collier's celebrated 'In the Bleak Midwinter' modulation — landing in G half-sharp, a key between the frets — is a different machine and worth keeping separate. There, four rising chords each hold a common tone with the chord before while everything else drifts microtonally sharp, so the ear is towed across a border no equal-tempered instrument can name. The diminished crossroads works in twelve-tone land and lives on your fretboard; the magical chords exploit tuning itself. Same instinct underneath both: keep one thing constant, and you can move everything else as far as you like.