Ah, spellbooks are SO much more useful than they appear. There are all kinds of crazy ways to make them work for you. Regular old fantasy tomes like you read about in Dungeons and Dragons are just kindling for the furnace compared with what a real tome can do. I won't spoil it here - you'll learn more ingame. For now, let's just say that using it as a notebook or diary is a simplistic (though valid) way to use this remarkable tool.