Why this strife of the chase? why weary, and palsy the arm at the oar, and the iron, and the lance? how the richer or better is Ahab now? Behold. Oh, Starbuck! is it not hard, that with this weary load I bear, one poor leg should have been snatched from under me? Here, brush this old hair aside; it blinds me, that I seem to weep. (from Moby Dick Source)
I'm having trouble understanding why the word that is used in the bolded part of this quote.