materials from some of the world's greatest violists. Music Reading music Music that is written for the viola primarily uses the alto clef, which is otherwise rarely used. Viola music employs the treble clef when there are substantial sections of music written in a higher register. The alto clef is defined by the placement of C4 on the middle line of the staff. In treble clef, this note is placed one ledger line below the staff and in the bass clef (used, notably, by the cello and double bass) it is placed one ledger line above. As the viola is tuned exactly one octave above the cello (meaning that the viola retains the same string notes as the cello, but an octave higher), music that is notated for the cello can be easily transcribed for alto clef without any changes in key. For example, there are numerous editions of Bach's Cello Suites transcribed for viola. The viola also has the advantage of smaller scale-length, which means that the stretches on the cello are easier on the viola. Role in pre-twentieth century works In early orchestral music, the viola part was usually limited to filling in harmonies, with very little melodic material assigned to it. When the viola was given a melodic part, it was often duplicated (or was in unison with) the melody played by other strings. The concerti grossi, Brandenburg Concertos, composed by J. S. Bach, were unusual in their use of viola. The third concerto grosso, scored for three violins, three violas, three cellos, and basso continuo, requires virtuosity from the violists. Indeed, Viola I has a solo in the last movement which is commonly found in orchestral auditions. The sixth concerto grosso, Brandenburg Concerto No. 6, which was scored for 2 violas "concertino", cello, 2 violas da gamba, and continuo, had the two violas playing the primary melodic role. He also used this unusual ensemble in his cantata, Gleichwie der Regen und Schnee vom Himmel fällt, BWV 18 and in Mein Herze schwimmt im Blut, BWV 199, the chorale is accompanied by an obbligato viola. There are a few Baroque and Classical concerti, such as those by Georg Philipp Telemann (one for solo viola, being one of the earliest viola concertos known, and one for two violas), Alessandro Rolla, Franz Anton Hoffmeister and Carl Stamitz. The viola plays an important role in chamber music. Mozart used the