developed by his followers, students are assigned koans by their teacher and then meditate on them. Once they have broken through, they must demonstrate their insight in private interview with the teacher. If the teacher feels the student has indeed attained a satisfactory insight into the koan, then another is assigned. Hakuin's main role in the development of this koan system was most likely the selection and creation of koans to be used. In this he didn't limit himself to the classic koan collections inherited from China. He is credited with one of the best-known koans, "You know the sound of two hands clapping; tell me, what is the sound of one hand?" (although Xuedou Chongxian's poetic commentary that "a single hand makes no clapping sound" appears 700 years as part of The Blue Cliff Record). Hakuin preferred this new koan to the most commonly assigned first koan from the Chinese tradition, the Mu koan. He believed his "Sound of One Hand" to be more effective in generating the great doubt, and remarked that "its superiority to the former methods is like the difference between cloud and mud". Four ways of knowing Asanga, one of the main proponents of Yogacara, introduced the idea of four ways of knowing: the perfection of action, observing knowing, universal knowing, and great mirror knowing. He relates these to the Eight Consciousnesses: The five senses are connected to the perfection of action, Samjna (cognition) is connected to observing knowing, Manas (mind) is related to universal knowing, Alaya-vijnana is connected to great mirror knowing. In time, these ways of knowing were also connected to the doctrine of the three bodies of the Buddha (Dharmakāya, Sambhogakāya and Nirmanakaya), together forming the "Yuishiki doctrine". Hakuin related these four ways of knowing to four gates on the Buddhist path: the Gate of Inspiration, the Gate of Practice, the Gate of Awakening, and the Gate of Nirvana. The Gate of Inspiration is initial awakening, kensho, seeing into one's true nature. The Gate of Practice is the purification of oneself by continuous practice. The Gate of Awakening is the study of the ancient masters and the Buddhist sutras, to deepen the insight into the Buddhist teachings, and acquire the skills needed to help other sentient beings on the Buddhist path to awakening. The Gate of Nirvana is the "ultimate liberation", "knowing without any kind of defilement". Opposition to "Do-nothing Zen" One