In the 8th and 9th centuries,within the ideal framework of the integration of Carolingian Empire and Christian Church,the ecclesiastical-secular relationship was both cooperative and competitive.Carolingian Specula Principum was a product of the mutual needs of the Church and the secular world.Secular power gained divine legitimacy to rule through Christian ethics,and the church participated in the political construction of the kingdom through moral discourse.The church elites wrote Specula Principum with the aim of admonishing monarchs and nobles to take up their duties as Christian rulers and to regulate their morality and behavior,thus building a society in line with Christian doctrines and canon law;at the same time,it also set moral boundaries for the secular power,and clarified the limitations of it.Specula Principum played an important role in the political development of the Carolingian dynasty,the promotion of Christian theory and the spread of culture,profoundly influenced the trend of Western European politics.