pianissimo, and the rustic glissando… is given a finicky elegance by the grace notes in the horns as well as by the doubling of the melody an octave higher with the solo violin. These details are not intended to blend, but to be set in relief; they are individually exquisite." Another example of Haydn's imagination and ingenuity that shows how well he understood how orchestration can support harmony may be found in the concluding bars of the second movement of his Symphony No. 94 (the "Surprise Symphony.") Here, the oboes and bassoons take over the theme, while sustained chords in the strings accompany it with "soft, but very dissonant harmony. " Flute, Horns and timpani add to the mix, all contributing to the "air of uncanny poignancy" that characterises this atmospheric conclusion. Mozart Mozart "was acutely sensitive to matters of instrumentation and instrumental effect where orchestral writing was concerned", including a "meticulous attitude towards the spacing of chords." H. C. Robbins Landon marvels at the "gorgeous wash of colour displayed in Mozart’s scores." For example, the opening movement of the Symphony No. 39 (K543) contains "a charming dialogue between strings and woodwind" that demonstrates the composer's exquisite aural imagination for the blending and contrast of timbres. Bars 102-3 feature a widely spaced voicing over a range of four octaves. The first and second violins weave curly parallel melodic lines, a tenth apart, underpinned by a pedal point in the double basses and a sustained octave in the horns. Wind instruments respond in bars 104–5, accompanied by a spidery ascending chromatic line in the cellos. A graceful continuation to this features clarinets and bassoons with the lower strings supplying the bass notes.Next, a phrase for strings alone blends pizzicato cellos and basses with bowed violins and violas, playing mostly in thirds:The woodwind repeat these four bars with the violins adding a counter-melody against the cellos and basses playing arco. The violas add crucial harmonic colouring here with their D flat in bar 115. In 1792, an early listener marvelled at the dazzling orchestration of this movement "ineffably grand and rich in ideas, with striking variety in almost all obbligato parts.""The main feature in [his] orchestration is Mozart’s density, which is of course part of his density of thought." Another important technique of Mozart's orchestration was antiphony, the "call and response" exchange of musical motifs or "ideas" between different groups in the