Lindsey: Will! Help! It is an utterly insurmountable paradox! I need to be able to recur over this list, but I also need to somehow know what was in the entire original list!
Will: You sure do.
Lindsey: If only I could keep track of the original list, say, by passing it around as an argument!
Lindsey: But the procedure is only supposed to take two arguments, so the only way to do it would be to write an entirely different procedure!
Lindsey: Woe betide us all! And then I would have to wrap that procedure in the original one, which takes two arguments!
Will: I think you got it.