This article explains Wittgenstein's distinction between good, bad, and vacuous modern music which he introduced in a diary entry from January 27, 1931. I situate Wittgenstein's discussion in the context of Oswald Spengler's ideas concerning the decline of Western culture, which informed Wittgenstein's philosophical progress during his middle period, and I argue that the music theory of Heinrich Schenker, and Wittgenstein's critique thereof, served as an immediate link between Spengler's cultural pessimism and Wittgenstein's threefold distinction. I conclude that Wittgenstein's distinction (...) between bad and vacuous modern music is analogous to Schenker's distinction between the compositional fallacies of the progressive and the reactionary composers of his time. Concomitantly, Wittgenstein's philosophically problematic notion of good modern music transcended the conceptual framework of both Schenker and Spengler. In this context, I examine Wittgenstein's remarks on Gustav Mahler as well as his remark on the music of the future as monophony, which, I conclude, should be understood ultimately as an ellipsis of his much later view of musical meaning and intelligibility. (shrink)