Maybe now is the time to learn German. Karl Corino's massive, 2000-page biography of Robert Musil was recently published, and apart from articles in the New Left Review and the TLS, I haven't seen much mention of it in my English-speaking circles. Philip Payne, who translated and edited the English reduction of Musil's diaries, did the TLS review, about half of which is present at that link.
For me it's tantalizing, since it relates something that remains very oblique even in the diaries, which is Musil's ongoing and shifting relation to the The Man Without Qualities, which he was creating for decades. I'm skeptical of the theorizing over Musil's syphilis and the hint that Musil wasn't especially good for his friends. Speaking about the brilliant but flighty and capricious Clarisse, from MWQ, and her real-life parallel Alice Donath, Payne says:
(Clarisse, like Alice, goes mad after her marriage and is eventually placed in an institution; one wonders whether Musil's wedding gift to Alice of Nietzsche's Collected Works, or his letter inviting her to become his "little sister" contributed to her troubles.)
But I'm intrigued by the talk of Musil's increasing isolation from his work's sources: not just temporally, but even personally, as he stopped associating with friends who had been the novel's models. This, however, seems secondary to Musil's situational problem, which is that history had left him behind:
In a letter of 1934 to his friend the satirist Franz Blei, Musil, given his desperate personal situation and the Nazi takeover in Germany, compares his continued work on The Man without Qualities to "the diligence of a woodworm, boring through a picture frame in a house that is already ablaze".
Musil's engagement with Arnheim/Rathenau is total, but by 1934, it could not have seemed relevant. He was attacking an Enlightenment-derived ideology in one of the better statesmen of the century while National Socialism had taken over the world around him. Excavation of a flawed "frame" was hardly noticeable while the house was on fire.
Musil treats the more extreme aspects in the later parts of the book, introducing the figure of Meingast, a faux-mystical shyster who plays like Kevin Kline quoting Nietzsche in A Fish Called Wanda. Meingast was loosely based on Ludwig Klages, a Spengler-ish conservative, anti-Semitic moron, deservedly forgotten. (I'd rather not link to the stuff that turns up, but if you'd like to be introduced to Klages and his unpleasant breathren such as Carl Schmitt, try looking for them on Google.) While Musil has some fun with Meingast (he's the only character who is really a caricature), you sense that his heart's not in it; Meingast is not a challenge. Anyone with a brain would hardly take him seriously. But anyone with a brain was in short supply.
(For an inexact modern parallel, I think of Richard Hofstadter's Anti-Intellectualism in American Life, where he condemns the anti-egghead attitude by pointing to how Eisenhower, the "normal guy" candidate, won twice over the wonky, detached Adlai Stevenson. Oh, for such days again....)
Musil wrote "On Stupidity" in 1937, a abstruse (for him) Benjamin-like exercise in postponement in which he never quite gets around to what he wants to say because it would get him in big trouble. I won't subject it to close reading here, but consider the very end of it:
For because our knowledge and ability are incomplete, we are forced in every field to judge prematurely; but we make the effort, and have learned to keep this error within recognized limits and occasionally improve on it, and by this means put our activity back on the right track. There is really no reason why this exact and proudly humble judgment and activity could not be carried over into other areas as well, and I believe that the principle, "Act as well as you can and as badly as you must, but in doing so remain aware of the margin of error of your actions!" would already be halfway toward a promising arrangement of life.
Update: Thomas Pynchon chimes in via Gravity's Rainbow, shortly before Rathenau is channelled by some Nazis and issues some cryptic mystical statements about industrialization, chemistry, and death:
His father Emil Rathenau had founded AEG, the German General Electric Compny, but young Walter was more than another industrial heir--he was a philosopher with a vision of the postwar State. He saw the war in progress as a world revolution, out of which would rise neither Red communism nor an unhindered Right, but a rational structure in which business would be the true, the rightful authority--a structure based, not surprisingly, on the one he'd engineered in Germany for fighting the World War. (165)