"However, as Schumann was pulling together his troops to combat silly theatre-music and vain displays of technical prowess, a much more dangerous foe was massing his forces on the horizon: the "Music of the Future," whose chief proponents were Liszt and Wagner. These sought to destroy music as a language of poetic ideas, the most efficient language with which to make the process of human creativity conscious for the listener, and instead made music the language of Eros -- of powerfully irrational sensual effects. In doing so they were attacking the very fundamentals of musical composition, and opening the door to the horrors of twentieth century music.
Schumann, in defense of music's fundamentals, invoked the greatest of poets, Bach and Beethoven:
"We yet need a publication to defend the 'music of the future.' Only such men as the late blind cantor of the Thomas School and the deaf conductor who lies in Vienna could aptly edit it."
Liszt and Wagner counterattacked against Beethoven himself, by revising and misperforming his works. Liszt produced abominable piano transcriptions of his symphonies and Wagner "revised" the famous Ninth. Schumann published the following one-sentence review of a performance of Fidelio in 1848:
"Bad performance; incomprehensible tempi taken by the conductor, Richard Wagner."
"Schumann attacked the compositions of Wagner on the grounds that they were simply bad music: in Schumann's words, "paltry, downright amateurish, formless, and repellent."
As can be seen by that Schuman thought Wagner was attacking the very foundations of great classical music. He view Wagner the way Varg might view Cradle of Filth. One can hardly say he thought Wagner great.