The Old Man and the Sea
Because the old man speaks alternatively to himself and to the fish, it is at times unclear to which he is speaking. This suggests there is not a lot of difference between the old man and the fish,
Despite overwhelming odds against him, the old man never gives up until the very end.
Although he "knows the fight is useless," the old man continues to battle the sharks anyway. This suggests he is fighting for some other motivation than "winning."