Composer's note: The 12th-century organa of the Notre Dame school (most notably those of Pérotin) employ plainchant as the slow foundation for rapid, ecstatic, dance-like melismata. In June 1994 I used this technique to write a very short piece for a Dutch project involving a two-octave musical box using only white notes. I dedicated the resulting 'Notre Dame des Jouets' to Peter Maxwell Davies on his 60th birthday and orchestrated it some months later. The second organum, dedicated to Reinbert de Leeuw, brings the same technique into a less 'innocent' world employing the total chromatic in elaborately grinding polyrhythmic layers. It should be heard with half an ear on the foreground activity and the other half on the extremely slow cantus firmus that defines its scale and resonances.