Wagner - Erster Aufzug (from 'Tristan and Isolde')

Musical Context Erster Aufzug comes from the opera 'Tristan and Isolde' which was composed by Wagner. Wagner (22 May 1813 – 13 February 1883) was a German composer, who was mainly known for his operas.^[1]   

In the opera there is the use of leitmotifs, which represent different forms of love and doubt. The leitmotifs only last for a couple of bars, but there are a few sections in the piece where they are repeated. 

Musical elements
  The cells open the piece playing the "Grief" motif, which is shortly followed by the oboes playing the "desire" motif. These motifs cause tension in the piece as they have been composed to create a dissonant chord. The cellos repeat the "Grief" motif, and the clarinets enter playing an imitation of the "desire motif". 

There is a not a clear key signature for this piece due to the many accidentals that are used, and also the facts that there is not a specific key signature notated. Having no clear key signature is typical of the romantic period. Although, the time signature of 6/8 remains the same throughout the piece. 

Musical Structure
Erster Aufzug is in a loose sonata form (Exposition, 'Middle section', and Recapitulation). The exposition is made up two themes. Theme 1 (measure 0-17) begins and ends in A minor, finishing with an interrupted cadence. Theme 2 (measure 17-24) starts in A minor, but then modulates through D and B minor to end on A major in bar 24 (first perfect cadence in the tonic).

The 'middle section' also has two parts to it (Section A and Section B). Section A (measure 24-32) begins with a new theme (theme 3), which begins in E major and then ends on the tonic note of A without a cadence. Section A ends with the repetition of bars 17-21 from Theme 2. Section B (measure 36-44) starts with antiphonal (A performance style in which an ensemble is divided into two or more groups, performing alternately as separate groups and in unison^[2]) development of a motif from theme 2. This section ends on a root position chord of A major. Finally, the 'middle section' ends with Section A1. This is a development of section A, and the dominant pedal on E (bars 63-70) helps to link this section to the recapitulation.

The recapitulation (1 and 2) is the final part of sonata form. Recapitulation 1 (measure 66-83) starts in A minor/major, but then modulates to Eb minor. This section ends (measure 77-83) with the contrapuntal (Using counterpoint. Any music that contains two or more voices heard simultaneously^[2]) combination of all three theme and the climactic 'Tristan chord'.




<sup>[1] http://en.wikipedia.org/wiki/Richard_Wagner#Operas

[2]</sup>  http://dictionary.onmusic.org/search?utf8=%E2%9C%93&term_search%5Bquery%5D=antiphonal&commit=Search

^{[3]  http://dictionary.onmusic.org/search?utf8=%E2%9C%93&term_search%5Bquery%5D=contrapuntal&commit=Submit}