Music for strings No.1, Op. 91

Based on the scale C Db Eb E F# G A Bb (or their enharmonics), also known as Messiaen's second mode of limited transpositions (M2). All the material of the piece is contained in the last 12 measures; it is just arranjed in several different ways between the parts, in the form of a long canon at the octave. The main melody appears for the first time in the bass, from measure 25 onward, then in the violas and lastly in the violins.