Ah, I see. Thank you very much. One final question, I think: I was trying to come at this by developing the proof for

, the same way they had come up with the proof for

. I wasn't having much success, but I can only assume that I was overlooking something (like that

thing). Otherwise, it would have yielded the same thing, right?

Once again, my thanks. I'm a little bit daunted by

*What is Mathematics?*. I've found it very engaging, but I occassionally feel like I'm punching above my weight with some of the exercises.