Hello Everybody !
I always thought about how do you actually learn a spell from the Spell Books you find all around..
Obviously you aren't absorbing the book like the game-play shows.
Actually there is a proof for that , when you go to Tel Mithryn at the first few visits , you can see Talvas Fathryon actually reading the book and trying to get the spell working.

So , how do you treat the spell books ?

Spell tomes should be treated like skill books. Read once for it's knowledge, then kept safe on a bookshelf. I treat it as if there are only a finite amount of spell tomes and they are imbued with great magic and power no matter the type or strength of the spell. And once all knowledge can be learned from said tome it becomes, "lost" for someone else to find. Somewhat like how unique items become lost over time from game to game and then these items turn back up with no explanation of how it came to be there. Thought it was a bit more creative than accidentally misplacing it or absorbing it...

An interesting thought.
I treat Spell Books as books with description ( That I make up.. ) and it takes my character a few in-game days to actually get it working.