"To attain buddhahood in the way of sudden enlightenment", "to understand the order of the Tian by meditation" and "to be a unity with Dao" are core ideas of Chinese Buddhism, Confucianism and Daoism. Chinese Buddhism, Confucianism and Daoism lay a common emphasis on enlightenment and meditation. The main reason is that the concepts of Buddha, Tian and Dao have something in common: They are eternal beings looked as "root of cosmos", "noumenon" and "the great whole" and have no define on their qualities, shapes , volumes and positions. The non-substantial nature of no umenon result s t he frangibility for common cognitional methods such as analysis , reasoning , induction and synthesis to grasp t he essence of noumenon. sudden enlightenment and meditation are cognitional methods of intuition that are developed during the long term of human practice. They try to speculate the noumenon as a whole directly. These cognitional methods have their rationality but lack of strict logical analysis and scientific proof . The intuitional enlightenment and meditation are methods of cognitional surmise and it means that t hey are not methods of necessity but feasibility.
