A thread like this deserves to be resuscitated. And books count, so I'll bite. Charles Rosen is probably best known for 'The Classical Style' (1971) and/or 'The Romantic Generation' (1995), but I found his little (114pp) book 'Arnold Schoenberg' (1975, 1981, 1996) to be a highly accessible and masterly introduction to Schoenberg himself as well as his pupils Berg and Webern -- full of insights unravelling the elusive role of this crux of composers in the development of modernism touching on topics ranging from the austrian culture of the day, to expressionism, romantic literature, through to the seminal influence of Wagner and Bach. A nice entrée to new music and much much more.