J.S.Bach’s Invention 8 BWV 779 arranged for violin and viola. One of the most popular of the two part inventions with scale runs and chord shapes to master. The sheet music score available as a pdf download from the website has pindividual parts appended to the full score. Accompaniments are also in place. An uplifting and appealing invention with many scale runs and chord shapes that make this an appropriate movement for guitarists to play to improve technique. There are some octave transpositions in the viola part to keep to the range of the instrument. The realisation plays back at 96 quarter note or crotchet beats to the minute. Many musicians play this invention faster and interestingly it is a movement usually played without ornaments. String players need to choose a tempo at which the whole movement can be played consistently. It is a good test piece for players because this piece can very easily run away with itself requiring a tempo adjustment in the challenging sixteenth /semi-quaver sections. Music cannot be played quickly until it can be played slowly. Ornaments are not generally featured in this movement whilst the realisation plays back at 96 quarter note or crotchet beats to the minute. Accompaniments are in place allowing violin and viola players to participate in ensemble activities as part of practice routines. The violin sounds on one side of the stereo channel and the viola on the other. The accompaniment tracks play back at, 84, 88, 92, 96, 100 and 104 quarter note (crotchet) beats per minute. This reflects the fact that this particular invention can be played at many different tempi. Accompaniment backing tracks are recorded with a dry acoustic to encourage accuracy in playing. There is a four bar count in /click track for each of the accompaniment tracks. It is wise for players to listen to performances of this invention on streaming media to understand the different approaches that players have when performing this movement especially with regard to articulation. The Bach Inventions are generally considered to be intermediate level movements when played on a keyboard instrument. They are possibly more challenging works when played on other instruments. The principle behind J. S. Bach’s two part inventions is to take a musical idea or motive and then process it following the rules of good contrapuntal writing using the compositional processes of the baroque and at the same time referencing the closely related keys in the harmonic journey. Inversion, repetition, sequence, transposition, rhythmic augmentation/diminution amongst other compositional processes and techniques are evident as in most other music of the baroque period. J. S. Bach composed 15 Inventions in a collection dating from 1723 intended to introduce keyboard players to composition techniques of the baroque. They are excellent pieces for developing ensemble playing in the duo format encouraging listening, accuracy in playing and good intonation.