Born in the late 9th century Baghdad, the ʿAbbāsid grammarian 'Abū Bakr Muḥammad b. Saḥl Ibn al-Sarrāj (d. 929), came to be remembered as the Banisher of Madness and the virtuous scholar whose life has exemplified the culture of Arabs in its fullness. Lauded as the arch-enemy of Hellenistic sciences and, at the same time, as the main source of transmission of Aristotelian logic from the 10th century philosophers to the grammarians of Baghdad; Ibn al-Sarrāj nonetheless remains a shadowy figure in the history of Arabic grammar studies up until today. This book addresses this issue by examining the problematic relationship between language, logic and grammar in Ibn al-Sarrāj's teachings. In addition, the present study offers an insight into the conflict between the medieval grammarians and logicians over the traditionally-established authority of ʿAbbāsid grammarians to analyse the intelligible realm and nature of a human soul. In order to come to terms with the controversial notion of grammarians as the guardians of the divine wisdom, the present study pivots on one of its greatest embodiment: Ibn al-Sarrāj's concept of the Wisdom of Arabs.