 Similarly, the third tier of Zhiyan’s panjiao stands to subsequent tiers as Dushun’s second discernment stands to his third, delving further into the nature of and relations among individual shi. But Zhiyan’s panjiao, unlike Dushun’s discernments, offers a doctrinal motivation for proceeding to higher stages. The motivation, in brief, is that no Mahayana teaching, elementary or advanced, explains both the origins of enlightenment and the origins of ignorance (as the main cause of barriers to enlightenment). Some Mahayana teachings ground the emptiness of reality upon something impure and tainted, laden with hindrances and defilements. These teachings accommodate ignorance. Yet they struggle to explain how enlightenment—pure and untainted—arises from the impure and tainted. Other Mahayana teachings ground the emptiness of reality upon something pure and untainted. Yet they struggle to explain how such a ground gives rise to hindrance and defilement. 