“Anything down there about your souls?”
“About what?”
“Oh, perhaps you hav’n’t got any,” he said quickly. “No matter though, I know many chaps that hav’n’t got any,- good luck to ‘em; and they are all the better off for it. A soul’s a sort of a fifth wheel to a wagon.”
Ishmael and Queequeq have just signed papers to sail on the Pequod when they meet an odd man in the streets. He asks them if they've signed on to sail with Ahab then gives them all kinds of hints about what a mistake that was. The title of the chapter is "The Prophet" - which should be a clue to readers. Later we find out the man's given name is Elijah. Elijah's comment about a soul being a fifth wheel is actually pretty brilliant. Sometimes when we make a decision, taking into consideration the afterlife and any ramifications, bogs us down. That seems to be what Elijah is telling Queequeq and Ishmael.