My master says not to judge a book by its cover, but it doesn't take an archmage to realize that his spellbook's a pretty nasty bit of business.
At first glance, you notice the silver needles along the binding dripping with poison while the dragonhide cover trails wisps of smoke, right?
But how many people would notice the howling bog-wraiths trapped as the bar code on the back?
I mean, who puts bar codes on the back of a spellbook? It's not you're going to want to list it on Amazon with an ISBN, right?
Archmages can be weird sometimes.