Neo-Confucianism signifies not only an established form of culture and knowledge, but also a unique and enduring philosophical spirit. The latter more correctly reflects the significance of Neo-Confucianism in the history of thought. The metaphysical difference between Cheng Hao and Cheng Yi lies mainly in their differing approaches to the ideal world and the living world. The difference directly constitutes the structure of mind in Neo-Confucianism. That is to say, Neo-Confucian approaches to mind require both the creation of significance and the perfection of personality. This can be seen as the analysis of the inner structure of mind and the metaphysical ideas of Neo-Confucianism. In this regard, the metaphysics of Cheng brothers exemplifies how to understand the difference between the ideal world and historicity in the structure of mind in Neo-Confucianism. This study also provides several examples of Confucianism‘s practical wisdom.