Why are books so big?

I have a perpetual fascination with manuscripts, marginalia etc. which makes me a frequent visitor to Got Medieval.  And here is an answer to a question which has been gently at the back of my mind for a number of years: why are books the size they are…

“The question then becomes, I guess, why were medieval books the size they were?  And the answer to that is simple: medieval books were the size they were because medieval sheep were the size they were.”

Visit: Got Medieval: Why are books so big? (Google Penance).