ETYMYTHOLOGY OF PARSIFAL -- Josef Görres (1813).

Speranza

Wagner's spelling of "Parsifal" instead of the "Parzival" he had used up to 1877 is informed by an erroneous etymology of the name "Percival" deriving it from a supposedly Arabic origin, "Fal Parsi" -- meaning "pure fool".

Wagner is following Josef Görres (1813).

See:

Richard Wagner,

Das braune Buch. Tagebuchaufzeichnungen 1865 bis 1882 ed. Joachim Bergfeld, Zürich, Freiburg i.Br. 1975, p. 52; Danielle Buschinger, Renate Ullrich, Das Mittelalter Richard Wagners, Königshausen & Neumann, 2007, p. 140.