This book details the life of one of the most important men of the tenth century, whose name is nevertheless unfamiliar to most young readers. Born in what is now Iraq, near the city of Basra, Ibn al-Haytham was a scientist during the golden age of Muslim civilization, and was the first to hypothesize that vision occurs when light beams travel through the lens of a human eye. Al-Haytham's work is significant because of his willingness to challenge old ideas in spite of resistance from other scientists and from the caliphate. Using systematic tests of his hypothesis, he created the Book of Optics that named parts of the eye and described the relationship of the eye and the brain, findings that are foundational to the field of medicine even today. Captions contextualize the colorful images that dot the text; these images include paintings, photographs of artifacts, and maps celebrating the glory of the golden age of Islam. A glossary defines words to know and includes images to explain each term.