The Hermaphrodite is described as a ‘chamber opera in seven parts’, but that’s only part of the story. The work is conceived as a ‘ballet-opera’ and in addition to its chamber ensemble and six vocal soloists (without fixed roles) it calls for two actors and any number of dancers. This is a theatrical piece in every sense but listening to an audio recording is an intense experience; much of the music is so physical that dance and movement fill your mind’s eye (and ear) involuntarily.

The work’s seven parts chart the faltering journey of a hermaphrodite into life, its struggle to accept itself and others (despite its beautiful effect on a group of men who attack it), its troubled journey to physical confidence, sexual awakening and eventual love. That journey is told clearly, brutally and tenderly by the various components but I have yet to get a handle on the symbolism of the epilogue, in which a man dives into the sea and copulates with an enormous female shark.

Nor is that an issue, because however absorbing Olav Anton Thommessen’s work is on the surface, it is surely filled with unknown unknowns that have yet to pose similar riddles. The music is spare, skeletal (often underpinned by careful, capering percussion) and tense. The use of singing voices as instruments to accompany spoken Norwegian creates the most tender of soundscapes, notably at the Hermaphrodite’s lurching retreats from sensuality (as in Act 1 part 4, ‘Desire’). Elsewhere the vocal writing is exceptional, as when soprano Eir Inderhaug quivers, splutters and then joins the wordless fabric of the ensemble in Act 2 part 1, ‘A Concert Chamber’.

The composer has a habit of alighting upon fertile textures and mining deep into them (as in that same movement’s entwined high-pitch ribbons on what sounds like flute and violin). Rarely are non-spoken voices foregrounded, but when they are – as when two cautiously approach one another in Act 2 part 3, ‘The Meeting’ – the effect is of pure nature music without a hint of contrivance.

Thommessen’s etched textures want to burst into expressionism in ‘Sleep’, the epilogue to Act 1, but he reins them in and the delicate equilibrium of the piece is preserved. In Act 2 part 2, ‘Insight’, the Hermaphrodite experiences playful impulses and accepts its duality; again Thommessen’s scoring is thrilling precisely because it is contained – the creature’s understanding remains limited. A moving and absorbing creation that proves even more so now, 40 years after it was written, given Western society’s journey down the very same paths (though we’ve yet to embrace bestiality with sharks).