[quote=@CaptainManbeard]
<Snipped quote by Lewascan2>

You could say at the beginning, the book has mostly blank pages and then the invisible ink gradually reveals itself as he levels up. Or maybe the book just magically grows new pages as he unlocks new spells from the grimoire or learns them from out in the world and copies the script. Also, feel free to spread your wings a little with magical abilities, since we're ending up with a little more freeform approach, I'm not gonna force anyone into the confines of any one class. For my evil wizard guy I was considering, I may fuse elements of Warlock into him as well and give his grimoire a living eye on the cover or something. We'll see. 
[/quote]

One way I also imagined it manifesting is that he's got all this blank space to fill up and does so himself. Like, consider that the first (highly expansive) part of the book is dedicated to education and walks you through everything you need to know one chapter at a time, and then when he learns stuff, it's up to him to actually successfully craft the spells and add them to his capabilities in the ever-growing spells section that takes up the rest of the book (and probably just grows new pages when needed). Depending on how intuitive this is, I assume the PCs all get a "starter boost", so he probably has a few spells he already knows right out the gate maybe, but going forward, most of the work is on his shoulders to actually be dedicated to the path of the Wizard. And yeah, with that go ahead, I think I'm definitely going to spread out his abilities to have him use necromancy for healing whenever he isn't poking the secrets to conventional healing magic. :)