Hey, it's fascinating to me to. Especially as purple is my favorite color.
I must tell you that when I saw your title, I immediately thought, "yeah! I've got to go check out this empurple guy -- If Peter says he 'shows the language's color', he must be a really great writer!". Then I realized that this wasn't "New and Noteworthy". Oh, well.
Kurt Messick wrote a couple of great reviews a while back on books about language. You might want to check those out. (No link, so I'm within bounds, right?) PM me if you can't find them.