Chromaticism Many music theorists have used Parsifal to explore difficulties in analyzing the chromaticism of late 19th century music. Theorists such as David Lewin and Richard Cohn have explored the importance of certain pitches and harmonic progressions both in structuring and symbolizing the work. The unusual harmonic progressions in the leitmotifs which structure the piece, as well as the heavy chromaticism of Act 2, make it a difficult work to parse musically. Notable excerpts As is common in mature Wagner operas, Parsifal was composed such that each act was a continuous flow of music; hence there are no free-standing arias in the work. However, a number of orchestral excerpts from the opera were arranged by Wagner himself, and remain in the concert repertory. The prelude to Act 1 is frequently performed either alone or in conjunction with an arrangement of the "Good Friday" music which accompanies the second half of Act 3, Scene 1. Kundry's long solo in Act 2 ("") is occasionally performed in concert, as is Amfortas' lament from Act 1 (""). Instrumentation The score for Parsifal calls for three flutes, three oboes, one English horn, three clarinets in B-flat and A, one bass clarinet in B-flat and A, three bassoons, one contrabassoon; four horns in F, three trumpets in F, three trombones, one tuba, 6 onstage trumpets in F, 6 onstage trombones; a percussion section that includes four timpani (requiring two players), tenor drums, 4 onstage church bells, one onstage thunder machine; two harps and strings. Parsifal is one of only two works by Wagner in which he used the contrabassoon. (The other is the Symphony in C.) The bells that draw the knights to the Grail ceremony at Monsalvat in acts 1 and 3 have often proved problematic to stage. For the earlier performances of Parsifal in Bayreuth, Wagner had the Parsifal bell, a piano frame with four strings, constructed as a substitute for church bells. For the first performances, the bells were combined with tam-tam and gongs. However, the bell was used with the tuba, four tam-tams tuned to the pitch of the four chime notes and another tam-tam on which a roll is executed by using a drumstick. In modern-day performances, the Parsifal bell has been replaced with tubular bells or synthesizers to produce the desired notes. The thunder machine is used in the moment of the destruction of Klingsor's castle. Recordings Parsifal was