Wagner's study of philosophy and spirituality gave his music-dramas a
depth and universality that sets them apart from most other works for the
musical theatre. Although RW lost interest in institutional religion
during his teens, he developed a lasting interest both in mysticism (both
in western mystics such as the Dominican Meister Eckhart, and in eastern
ones such as the Sufi poet Hafiz) and in that part of philosophy closest
to theology. He dedicated his essay, 'The Art-Work of the Future' (1849)
to Ludwig Feuerbach, the philosopher and author of 'The Essence of
Christianity'.  Commentators have seen the influences of Feuerbach's 
philosophy of religion and of Hegel's philosophy of history in the 'Ring'.

Five years later, a friend introduced him to the writings of another
philosopher, Arthur Schopenhauer, whose 'The World as Will and
Representation' he read four times in less than a year. This book not only
revealed to RW the meaning of his own 'Ring' poems, but led him to write
new texts (notably 'Tristan und Isolde') that deal with human existence in
terms of this philosophy. Infected by Schopenhauer's interest in Indian
religions, RW began to study books on this subject recommended by
Schopenhauer.  These studies led him to begin a work that he never
completed, the Buddhist drama 'Die Sieger', and to another which he did,
'Parsifal'.