Describing Icelandic composer Anna Thorvaldsdottir's Enigma – her first string quartet – is not easy, but imagine you're suspended in some primordial gas cloud where matter is transforming, regenerating, building toward the birth of a planet. In the final section of the half-hour piece, long arcs of shifting sound deliver melodies in slow motion, while the composer's extended techniques for the players can make a violin sound like a woodwind or a synthesizer. Percussive creaks and snaps collide with slippery glissandos that flash across the score like tails of cosmic particles in the black nothingness. The performance, by the Spektral Quartet, makes the music feel vast and intimate at once. In an introduction to the score, Thorvaldsdottir dispenses some colorful advice: "When you see a long sustained pitch, think of it as a fragile flower that you need to carry in your hands and walk the distance on a thin rope without dropping it or falling." Good luck.