I tried reading Nietzsche's "Thus Spake Zarathustra" when I was in college and we were all on the "2001" kick. It struck me as raving gibberish even though it was apparently in English. A few weeks ago I mentioned it to a friend and was relieved when he said he'd also found it incomprehensible. And all these years I thought I was intellectually stunted.
Had to read something by Richard Wagner once upon a time. Vast tedious stretches interrupted by pages and pages of stuff you could go crazy trying to understand, even though it was apparently in English. His music can be pretty tedious to the neophyte, also, but it has long stretches of unimaginably beautiful passages (listen to the last twenty minutes or so of "Die Walkure"), interspersed with sex and violence, so you can listen to it repeatedly and finally end up enjoying the whole thing. Too bad his philosophy doesn't have more sex and violence, 'cuz maybe then I'd try rereading it and I could figure out what the hell he was talking about
Then there's Kurt Vonnegut's "Timequake". Here's part of what I said on amazon.com about the first Vonnegut book I never finished:
"But this is what happens when you take a short story (or more accurately, the bits and pieces of a short story) and mix it in a salad bowl with other ideas for a short story, along with some family reminiscences and your general cranky views of life. It starts nowhere, goes nowhere, and although I gave up on it about 3/4 of the way through, I'll bet my next paycheck that it arrives nowhere.
"If you decide to read this mess anyway, ask yourself what would have happened to the manuscript if it had originally arrived on a publisher's desk with your name on it instead of Vonnegut's."