The hand finds the voice.
Voice leading is a topology your hand can feel. Drag a triad along the inner ring for P, L, or R — single-voice motion. Pull past the ring for the compound transforms — H, N, S — where two or three voices travel at once.
Most theory tools are visual-intellectual. You read a diagram, you nod, you do not feel the structure. Embodied cognition research says music is learned through the body — through gesture, through breath, through the hands.
This page is a single experiment. One triad. Three spokes. Up is P (parallel — flip major and minor on the same root). Down-right is R (relative — share the major-third edge). Down-left is L (leading-tone — share the minor-third edge). The direction picks the transform; the length commits it.
Each PLR transform keeps two voices still and moves one — that is the whole point. Common tones draw a flat green line. The moving voice draws an arc whose height matches the distance. The arc IS the voice.
C major → A minor (R): common tones C and E, one voice slides up a whole tone. Two flat lines, one short amber arc. C major → C minor (P): keep root and fifth, third drops a semitone. Two flat, one tight violet arc. Your hand learns the topology by drawing it.
A common tone. The voice does not move. Every PLR transform keeps two voices still — that's why they sound smooth. Two flat lines, one moving arc.
Stepwise motion — one or two semitones. P and L produce these: a single voice steps by half-step or whole-step. The shortest harmonic motion the ear knows.
A leap — three or more semitones. Rare in single PLR steps; appears when the optimal voicing has to jump an octave to keep voices close. Compound chains can produce them.
Past the inner ring. H=LPL is the hexatonic pole — no common tones, every voice moves (C major → G# minor). N=RLP keeps the root, two voices step (C major → F minor). S=LPR keeps the third, two voices slide a semitone (C major → C# minor). Arcs recolor in the spoke's hue to mark "this is not a single PLR step."