Born in the late 9th century Baghdad, the ʿAbbāsid grammarian ‘Abū Bakr Muḥammad b. Saḥl Ibn al-Sarrāj 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.