The Abbasid poet and literary theorist Ibn al-Mutazz explores a new territory of literary enquiry by identifying a new 'poetics' which had emerged with the 'modern' poets of the second and third centuries of Islam. Writing on aspects of language and balaghah in general was, however, very much in evidence from the end of the second/eighth century; but the works produced were either outside the domain of poetry, or treated of poetry externally, in ways which had little bearing on the development of poetics, literary theory or literary criticism. The issue of the inimitability of the Quran, which was to be of central importance for literary criticism, was not an external one, since ijaz was proclaimed by the Book itself. This chapter deals with specific aspects of the work of five major figures, placing emphasis on features which constitute each one's individual contribution. They are Ibn Tabataba, Qudamah b. Jafar, al-Amidi, Al-Qadi l- Jurjani, and Abd al-Qahir al-Jurjani.