Iván Fischer and the Budapest Festival Orchestra conclude their highly acclaimed Mahler cycle with Symphony No.7. Often referred to as ''The Song of the Night,'' this subtitle was not Mahler's own. It grew out of the composer's comparison of the first movement to Rembrandt's painting The Night Watch. The symphony's structure and scoring are unique. Although listed as being in E minor, the work returns to the ideal of 'progressive tonality' which Mahler had abandoned in the Sixth.