 Among his several hundred books and treatises, Ringstones and Openings are the most famous. Ringstones became the standard text to transmit his teachings and, during the next six centuries, was the object of more than a hundred commentaries. Among his many talented disciples, the most influential was his stepson Sadr al-Dîn Qûnawî (1210–74), who began the process of systematizing his teachings and elucidating his perspective in conversation with contemporary philosophy, even initiating a correspondence with Nasîr al-Dîn al-Tûsî, the important reviver of Avicenna (Qûnawî, al-Murâsalât).