Mafatih al-Ghayb, usually known as al-Tafsir al-Kabir, is a classical Islamic tafsir book, written by the twelfth-century Islamic theologian and philosopher Fakhruddin Razi (d.1210). The book is an exegesis and commentary on the Qur'an. At 32 volumes, it is even larger than the 28-volume Tafsir al-Tabari. It is not unusual for modern works to use it as a reference.One of [his] major concerns was the self-sufficiency of the intellect. [...] [He] believed [that] proofs based on tradition (hadith) could never lead to certainty (yaqin) but only to presumption (zann), a key distinction in Islamic thought. [...] [However] his acknowledgment of the primacy of the Qur'an grew with his years. [...] [Al-Razi's rationalism] undoubtedly holds an important place in the debate in the Islamic tradition on the harmonization of reason and revelation. In his later years, he also showed interest in mysticism, although this never formed a significant part of his thought.