Besides 'Infinite Jest', 'Ulysses' has been one of the most challenges works of fiction that I read. While works such as '2666' and 'Infinite Jest' are thought provoking, they both were quite depressing reads, making them both hard for me to want to pick-up again. Though I recommend both. 2666 to explore concepts in modern art, and Infinite Jest to witness the insanity of intelligence agencies. Ulysses, on the other hand, I will probably study off and on until death.