I deny that either singers or conductors can "create" or work creatively - this, as I have always said, is a conception that leads to the abyss.
Letter to Giulio Ricordi (April 11, 1871) quoted in "Giuseppe Verdi" (1959) by Franco Abbiati, Milano: Ricordi, vol. 3, (p. 448), translated by Edward Downes in "Verdi: The Man in His Letters" edited by Franz Werfel and Paul Stefan, New York: L. B. Fischer, (pp. 301-302), 1942.