By the time of his release, Alhazen had written most of his seven - volume Book of Optics, considered to be “one of the most important books in the history of physics. ”
او برای فرار از مجازات خلیفه که به بی‌ثباتی و دمدمی‌مزاجی معروف بود ،‏ تا زمان مرگ خلیفه در سال ۱۰۲۱ برای ۱۱ سال خود را به دیوانگی زد .‏