I'm currenly doing an English literature PhD. Occasionally, I suffer from doubts that my entire subject is sheer intellectual wankery, and that I should have been A Scientist Doing Useful Stuff For The Good Of Humanity.
Then I remind myself that my dad's a scientist, and that his PhD is on the urinary tract of the flounder. Working women in Weimar Germany versus fish pee - yeah, there's not actually a lot to choose between them! --biascut in this linguaphiles post.