Al-Khwārizmī authored a work on Arabic grammar, Kitāb kifāyat al-Mutaḥaffiẓ [A Classified Vocabulary of Rare of Difficult Arabic words]. However, he is best known as the author of Mafātīḥ al-ʿulūm (The Keys to the Sciences), an early Islamic Encyclopedia of the Sciences.[9] A monumental work, Mafātīḥ al-ʿulūm is part lexicography and part encyclopedia.[10] Scholars regard it as the first attempt to document the Islamic sciences.[11] The work includes sections on mathematics, alchemy, medicine and meteorology.[12]