The great Majmoo’ al-Fatawa (Compilation of Fatawa) was collected centuries after Sheikh Al-Islam’s death, and contains several of the works he was known to author. So, it is a comprehensive scientific collection that covers all fields of knowledge, whether that be in the area of ‘Aqeedah, Tawheed, Fiqh, Usul, Hadith, Tafseer, astronomy, logic (Mantaq) and debate, knowledge of various sects and denominations, medicine, the Arabic language, geography, history, spirituality, and much more.