I want to know a thing, page 79 for xizard there is noted that "He cannot prepare any spell not recorded in his spellbook, except for read magic, which all wizards can prepare from memory" but page 490 it is said that "The writing on a scroll must be deciphered before ... requires a read magic spell or a successful Spellcraft check (DC 20 + spell level)."
So I don't understand a thing, if all wizard can prepare from memory Read Magic, why can't they decipher a scroll even if they have not prepared that spell during the morning ?
I want to know a thing, page 79 for xizard there is noted that "He cannot prepare any spell not recorded in his spellbook, except for read magic, which all wizards can prepare from memory" but page 490 it is said that "The writing on a scroll must be deciphered before ... requires a read magic spell or a successful Spellcraft check (DC 20 + spell level)."
So I don't understand a thing, if all wizard can prepare from memory Read Magic, why can't they decipher a scroll even if they have not prepared that spell during the morning ?
Read Magic is a way to magically understand a scroll, while spellcraft is the mundane way. They know how to prepare the spell from memory, but they still need to prepare it to be able to cast it. If they don't prepare it, they have to try to understand it the mundane way. Preparing a spell isn't really "memorizing" it anymore as it was in previous D&D incarnations (2e and before, I think) - now, most of the spellcasting is done when you prepare it and the casting is just uttering the final syllables, basically.
EDIT: Note though, that the wizard can leave some preparation slots open, and prepare it from memory when he needs to. That takes 15 minutes though.