Understanding the harmonic rhythm also helps to identify the 'gestures' or expressive units within the piece. In the following clip, Ruth demonstrates how the underlying G major harmony in the first half of bars 1 and 4 helps us interpret the notes as being part of one gesture, and to perform it accordingly.

The progression of the implied harmony is one way in which the composer builds tension and release into the piece. In the first four bars of both the Prelude and the Allemande, the music takes a journey from a G major, via a number of other chords, before coming back to G major again. You will be able to hear the tension increasing in bar 3, with the introduction of the F-sharp diminished chord, particularly in the Prelude, when the pedal G (the note which repeatedly begins each bar) forms a dissonance with the implied chord. This tension is released when the music returns 'home' to G major. You will notice that Ruth plays the dissonances more strongly, and performs a diminuendo at the release point in both movements. It helps to identify these points of tension and release throughout the piece. It can be tempting to overplay the mass of black notes on the page, but once you have found the major dissonances and resolutions, you can start to find good places to increase the dynamic and the energy, and places where it is better to 'let go'.

In the following extract, from Vivaldi's Sonata in A minor (RV44), Ruth demonstrates how the harmonic structure helps us to give shape to a phrase, even when it is complicated by syncopation. The chords change twice per bar, so Ruth suggests playing strongly at the beginning of each chord change (on the bar and half bar), and then playing more lightly as each gesture progresses:

Another example of the ways in which slurs contribute to the character of a piece is demonstrated in an arrangement for Cello of 'Es is vollbracht' from Bach's St John Passion. Here, a lean at the beginning and diminuendos through the slurred appoggiaturas emphasise the dissonant notes, giving them a sense of yearning.

The shape of the baroque bow gives slurs played with a down-bow a natural diminuendo. When playing this and similar passages with a modern bow, you will need to make a conscious effort to diminuendo through a slur.