How much can be written about knitting?

Quite a lot, it seems. First, I learned about Stephanie Pearl-McPhee . Then my friends Betty and Ann invited me to a book signing by Amy R. Singer. Her book, no sheep for you, is all about knitting with non-sheep's-wool fibers. In her words, anything that never had 4 legs. I didn't realize the disasters that could happen by substituting the wrong fiber for wool, depending on the project and type of fiber used. I'll give a better review later, after I've had time to review this book.