In the Islamic epistemology Islamic Golden Age which was booming prior to the Age of Enlightenment in Europe. One of the most prominent and influential philosophers, theologians, jurists, logicians and mystics Abu Hamid Al-Ghazali wrote over 70 books, including his best-known work in 1107 CE, his spiritual autobiography, "Deliverance from Error" (Al-Munqidh min al-Dalal). In this book Al-Ghazali was seeking to know what we can be certain about: what is true knowledge and not just opinion? To accomplish this goal, he would first consider what kinds of things we can know. This involves a study of epistemology, the theory of knowledge.