The two works of Joseph Schwantner which are the focus of this study, are quite unique for this composer. These two pieces represent the only instance in which Schwantner used the same music for two different compositions. From a Dark Millennium, and Sanctuary from the Music of Amber, are identical in musical material, form and length. While From a Dark Millennium was written for a large wind ensemble, Sanctuary was scored for a sextet of flute, clarinet/bass clarinet, violin, cello, piano, and percussion. The comparative analysis of these pieces reveal the essence of the music, as well as explores the scoring of each version. Both the melodic and harmonic material in this music is based almost entirely on an octatonic scale of alternating whole and half steps. Very little musical material is used in these works, however the approach toward expanding this material is exceptionally creative. The music shifts abruptly from sections that are sparse and soloistic, to scoring that is very dense. While the piano is utilized as the central timbre in both versions, the wind ensemble presents a much heavier and more percussive sound throughout. The chamber version, due to its size and instrumentation, is more ethereal, and features the performers in a soloistic environment. In examining both of these works, many of the distinctive traits found in the music of Joseph Schwantner are exhibited. The differences between these two versions help to illustrate his unique approach to composition and orchestration. The two works have also had a significant impact in their respective performance media as well. From a Dark Millennium has become an important part of the repertoire for wind ensembles; and Music of Amber, which won the 1981 Kennedy Center Friedheim Award for excellence in chamber composition, is one of Schwantner's most performed chamber pieces.