A singer whose ear is singly directed to the melodic aspects of a Brahms lied or a Verdi aria lacks perception of the musical web from which the melodic line emerges; the composer's intent may remain unrealized. to sing Schubert, Schumann, Brahms, Wolf, or Strauss lieder without an understanding of underlying harmonic structures is to vocalize on them, not to conceive of them musically and emotionally.
Richard Miller, Solutions for Singers: Tools for Performers and Teachers
music, voice