 Zhu Xi’s teacher, Li Tong, and friend, Zhang Shi (1133–1180), presented him with different approaches to cultivation based on the premise of basic still and active mindsets, respectively. But, Zhu found that both of these approaches were one-sided and flawed. How is one to leap from quiet-sitting and stillness to making timely moral responses? When does one have the composure to introspect morally when their mind is constantly active and engaged? If neither the meditative approach nor the active approach to cultivation and practice were efficacious, what path remained open to Zhu Xi? Recent research shows that Zhu Xi embarked on a careful reading of the works of Zhou Dunyi during this period of spiritual-philosophical crisis in the course of which he rediscovered Zhou’s doctrine of “the interpenetration of stillness and activity” for the human mind and spirit (Adler 2014). With this idea, Zhou Dunyi was advocating that whereas the states of action and rest are mutually exclusive in the case of physical objects, such states interpenetrate and are mutually implicative in the case of human mental and spiritual phenomena (Adler 2014). This doctrine piqued Zhu Xi’s interest, and he came to see it as offering a way out of the dilemma between Li Tong’s stress on stillness and Hu Hong’s stress on activity in cultivation and practice, and their respective shortcomings. Zhou Dunyi’s doctrine was particularly exciting to Zhu Xi for it highlighted the distinctness and potential religiosity of the human mind and spirit, which Zhou describes as not subject to the same limitations and restrictions as are physical phenomena. Zhou Dunyi moreover associates this idea with a vital and well integrated model of human mind and spirit, self-cultivation, and cosmos. Inspired by Zhou Dunyi’s doctrine of the interpenetration of stillness and activity and related ideas, Zhu Xi worked out a twofold cultivation effort that incorporated at once nurturing one’s feeling of reverence (jing) to purify mind while investigating things to discern their determinate or defining patterns (li). Cultivation of reverence, originally a religious virtue associated with ancestor worship and ceremonial rites, as described in the classics and taught by Confucius (551–479 BCE), serves to purify the mind, attune one to the promptings of the original good nature, and set one to act with appropriateness (yi). Moreover, by grasping the defining patterns (li) of relationship and intercourse that constitute the world, society, people, and proper conduct, one gains the master key to acting with utmost propriety (zhongyong). The mind that is imbued with reverence and comprehends these patterns will develop into a good will (zhuzai) dedicated to acting appropriately and with utmost propriety. Since jing takes on connotations of focus, concentration, and alertness, as well as reverence in Zhu Xi’s discourses, mindfulness has been suggested as the English translation that covers the fullness of the term jing (Kalton 1988) in Zhu Xi’s thought.