  From the Tang period, one begins to find serious attempts to collect and classify the growing number of Laozi commentaries. An early pioneer is the eighth-century Daoist master Zhang Junxiang, who cited some thirty commentaries in his study of the Daodejing (Wang 1981). Du Guangting (850–933) provided a larger collection, involving some sixty commentaries (Daode zhenjing guangshengyi, Daozang no. 725). According to Du, there were those who saw the Laozi as a political text, while others focused on spiritual self-cultivation. There were Buddhist interpreters (e.g., Kumārajīva and Sengzhao), and there were those who explained the “Twofold Mystery” (chongxuan). This latter represents an important development in the history of interpretation of the Daodejing (Assandri 2009).