What thoughts of Mencius laid the foundation of Confucian moral metaphysics?

Mencius viewed the relationship between heaven and man from the perspective of the theory of good nature, and put forward the philosophical thought of "being single-minded, intellectual and knowing heaven" Mencius transformed the heaven in the sense of personality god in the traditional view of destiny into the "heaven of righteousness and reason" in the ethical sense, and endowed it with moral attributes. He believes that people's good qualities, such as benevolence, loyalty and faithfulness, all fall from the sky. "Kindness, loyalty and tireless kindness are also heavenly kings." "Benevolence, the Lord of heaven." ("Mencius Gongsun Chou") Heaven has goodness such as benevolence and righteousness, and the goodness in human nature actually comes from the goodness in nature. On the point of good nature, heaven and man are one. He pointed out that as long as we sincerely expand the innate goodness, we can understand human nature and understand the nature of human goodness, that is, the nature of heaven. This is the so-called "those who do their best know their nature;" If you know its nature, you will know its sky. " He regards "keeping pace with the world" and "everything is ready" as the highest realm of moral cultivation. Only entering this realm is the greatest happiness in life, "reflexive and sincere, happy." "