DISCUSSIONS on “Rules for online games in HoMM3 and formulas for calculating player rating.”

Is it necessary for this hero to learn the spell? If he doesn't have enough wisdom, or even a spellbook, then what?

Read the entire section 5.10, instead of quoting just one phrase from it.
If the Hero doesn't have a spellbook, how can he use magic? Ask more specifically, because the question is unclear.