What does this mean "the damage that Wagner had inflicted upon Western culture"??!?!
He means the anti-rational, anti-enlightenment, and anti-Western philosophy that inspired it.
You know, the anti-individualist, anti-capitalist, collectivist evil that was responsible for the deaths of 165 million people at the hands of their own governments.
Socialism, fascism, communism, anarchism, totalitarianism, etc.
That damage.