Just in time to close 2017 with a microtonal bang!, composer Taylor Brook released Virtutes occultae: an exploratory double album for piano. Somewhere between procedural, improvised, and strictly composed, the eighteen parts of this magnum opus take you into the world of overtonality. In a nutshell, this album is played by six virtual pianos, each tuned to a different 11-limit just intonation tuning. The details on how Brook’s approach extends Partch’s are scarce and blurry, but, in any case, the result is utterly mesmerizing. The fact that the music is played only by pianos, virtual ones at that, is never an obstacle or a flaw that needs to be addressed. To the contrary, I believe that the piano’s relatively simple and “pure” timbre puts the notes at the forefront, and allows the listener to gaze into the lattice interactions and not get distracted by anything other. At over an hour and a half, it’s a massive chunk, and quite a lot to digest, but the minimal instrumentation and the sheer beauty of the pieces make it seem like a breeze. Virtutes occultae is a masterpiece.