Shepherd's Song is heard in the prelude to the Finale, Act 3 of Wagner's great opera, Tristan and Isolde. It is a bleak and doleful lament played mostly unaccompanied by a shepherd boy keeping watch for Isolde's ship to arrive. The melody is later heard throughout scene 1.
Ralph Sauer, has done a beautiful job in arranging this music (originally played offstage on the English Horn) for Euphonium in bass clef.
It is about 2 1/2 minutes in length and appropriate for advanced performers.