You have mastered a small handful of spells, and can prepare these spells without referencing your spellbooks at all.
Each time you take this feat, choose a number of spells that you already know equal to your Intelligence modifier. From that point on, you can prepare these spells without referring to a spellbook.
Without this feat, you must use a spellbook to prepare all your spells, except read magic.
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SECTION 15