Progressive tonality is the music compositional practice whereby a piece of music does not finish in the key in which it began, but instead 'progresses' to an ending in a different key or tonality. In this connection 'different key' means a different tonic, rather than merely a change to a different mode (see: Picardy third and List of major/minor compositions): Gustav Mahler's Second Symphony (1888–94), for example, which moves from a C minor start to an E-flat major conclusion, exhibits 'progressive tonality'—whereas Ludwig van Beethoven's Fifth Symphony (1804–08), which begins in C minor and ends in C major, does not. A work which ends in the key in which it began may be described as exhibiting 'concentric tonality'. The terms 'progressive' and 'concentric' were both introduced into musicology by Dika Newlin in her book Bruckner, Mahler, Schoenberg (1947).[1][2]