Throughout Chinese history, "Emperor" (Chinese: 皇帝; pinyin: Huángdì) was the superlative title held by the monarchs of imperial China's various dynasties. In traditional Chinese political theory, the emperor was the "Son of Heaven", an autocrat with the divine mandate to rule all under Heaven. Emperors were worshiped posthumously under a secular imperial cult. The lineage of emperors descended from a paternal family line constituted a dynasty, and succession in most cases theoretically followed agnatic primogeniture. The emperor of China was an absolute monarch, though in the late Qing reforms plans were made to move the emperor to a constitutional monarch.
During the Han dynasty, Confucianism gained sanction as the official political theory. The absolute authority of the emperor came with a variety of governing duties and moral obligations; failure to uphold these was thought to remove the dynasty's Mandate of Heaven and to justify its overthrow. In practice, emperors sometimes avoided the strict rules of succession and dynasties' purported "failures" were detailed in official histories written by their successful replacements or even later dynasties. The power of the emperor was also limited by the imperial bureaucracy, which was staffed by scholar-officials, and eunuchs during some dynasties. An emperor was also constrained by filial obligations to his ancestors' policies and dynastic traditions, such as those first detailed in the Ming-era Huang-Ming Zuxun (Ancestral Instructions).
