So I read this at 3 am, after finishing some math homework, and my first thought is, “Wow, that title’s one of the best!” and then I had to wrap my head around a mental image of things converging by iteration before I could get on with the story (I really hate my brain sometimes, I am such a nerd).
The story matched the title in brilliance, however, once I focused on the important thing. The dialogue between Harry and Snape was superb, and had me smirking more than once.