Medieval Arab scholars held grammar in very high esteem due to two main reasons. First, intellectual curiosity led them to investigate the language and its structures. Secondly, the desire to better understand the holy text of the Qur an made Arabic grammar indispensable. The intellectual curiosity as well as the interconnection between grammar and the study of religion can be seen in the grammarians' writings and theories in general and in this book in particular. The book consists of a critical edition and the analysis of an early treatise in the field of Arabic grammar, based on two manuscripts located in England and Egypt. The work's title is Mizan al-arabiyya which literally means 'the balance, or scales, of Arabic.' It is a pedagogical work dedicated to Arabic grammar and written by the famous Arabic grammarian Ibn al- Anbari (died 577/1181) who is probably best known for his al- Insaf fi masa il al- ilaf bayn al-nahwiyyin al-basriyyin wa-l-kufiyyin, a collection of Streitfragen (controversial issues) attributed to the Basran and Kufan grammarians. Among his rather few other extant treatises is the celebrated Asrar al-arabiyya, mostly dedicated to theoretical reasoning behind linguistic facts. In addition to the critical edition of Mizan al-arabiyya, the book also contains a detailed comparison between this work and the above-mentioned Asrar al-arabiyya, both written by the same author.