The key to the understanding of Chinese art, is the understanding of the Chinese history and to this, the notion about the "Mandate of Heaven" or - the rulers right to rule, is of critical importance. For further information, see my section on Chinese History or my LINKS page to other web resources. For a start, here is one of the more important source texts, taken from The Sacred Books of China: The Texts of Confucianism.
In the twelfth month of the first year . . . Yi Yin sacrificed to the former king, and presented the heir-king reverently before the shrine of his grandfather. All the princes from the domain of the nobles and the royal domain were present; all the officers also, each continuing to discharge his particular duties, were there to receive the orders of the chief minister. Yi Yin then clearly described the complete virtue of the Meritorious Ancestor [Cheng Tang, founder of the Shang Dynasty] for the instruction of the young king.
He said, "Oh! of old the former kings of Xia cultivated earnestly their virtue, and then there were no calamities from Heaven. The spirits of the hills and rivers likewise were all in tranquility; and the birds and beasts, the fishes and tortoises, all enjoyed their existence according to their nature. But their descendant did not follow their example, and great Heaven sent down calamities, employing the agency of our ruler' who was in possession of its favoring appointment. The attack on Xia may be traced to the orgies in Ming Tiao [the last of the Xia rulers]. . . . Our king of his sagely prowess; Shang brilliantly displayed for oppression he substituted his generous gentleness; and the millions of the people gave him their hearts. Now your Majesty is entering on the inheritance of his virtue; - all depends on how you commence your reign. To set up love, it is for you to love your relations; to set up respect, it is for you to respect your elders. The commencement is in the family and the state. . . .
"Oh! the former king began with careful attention to the bonds that hold men together. He listened to expostulation, and did not seek to resist it; he conformed to the wisdom of the ancients; occupying the highest position, he displayed intelligence; occupying an inferior position, he displayed his loyalty; he allowed the good qualities of the men whom he employed and did not seek that they should have every talent. . . .
"He extensively sought out wise men, who should be helpful to you, his descendant and heir. He laid down the punishments for officers, and warned those who were in authority, saying, 'If you dare to have constant dancing in your palaces, and drunken singing in your chambers, - that is called the fashion of sorcerers; if you dare to set your hearts on wealth and women, and abandon yourselves to wandering about or to the chase, - that is called the fashion of extravagance; if you dare to despise sage words, to resist the loyal and upright, to put far from you the aged and virtuous, and to seek the company of . . . youths, - that is called the fashion of disorder. Now if a high noble or officer be addicted to one of these three fashions with their ten evil ways, his family will surely come to ruin; if the prince of a country be so addicted, his state will surely come to ruin. The minister who does not try to correct such vices in the sovereign shall be punished with branding.'
"Oh! do you, who now succeed to the throne, revere these warnings in your person. Think of them! - sacred counsels of vast importance, admirable words forcibly set forth! The ways of Heaven are not invariable: - on the good-doer it sends down all blessings, and on the evil-doer it sends down all miseries. Do you but be virtuous, be it in small things or in large, and the myriad regions will have cause for rejoicing. If you not be virtuous, be it in large things or in small, it will bring the ruin of your ancestral temple.
Source: James Legge, trans., The Sacred Books of China: The Texts of Confucianism, in F. Max Mueller ed., The Sacred Books of the East, 50 vols., (Oxford: Clarendon Press, 1879-1910, vol., 3, pp. 92-95