you feel like an evil, slinking miscreant?
-Crime and Punishment
you feel depressed
-do atlases count? if not I'd say The Picture of Dorian Gray for its verbosity and frills or a historical nonfiction (history makes me feel "a part of" and my problems seem fairly insignificant.
you feel at a loss of words
when you want to read your favorite book of all time
-my bible, i.e. The Brother's Karamazov