The Libri Carolini ("Charles' books"), Opus Caroli regis contra synodum ("The work of King Charles against the Synod"), also called Charlemagne's Books or simply the Carolines, are the work in four books composed on the command of Charlemagne, around 790, to refute the supposed conclusions of the Byzantine Second Council of Nicaea (787), particularly as regards its acts and decrees in the matter of sacred images. They are "much the fullest statement of the Western attitude to representational art that has been left to us by the Middle Ages".
The Libri Carolini were never promulgated at the time, and remained all but unknown until they were first printed in 1549, by Jean du Tillet, Bishop of Meaux, under the name of Eriphele. They seem not to be the version which was sent to Pope Adrian I, who responded with a grandis et verbosa epistola (dignified and wordy letter). They contain 120 objections against the Second Council of Nicaea, and are couched in harsh, reproachful terms, including the following: dementiam ("folly"), priscae Gentilitatis obsoletum errorem ("an old and outmoded pagan misunderstanding"), argumenta insanissima et absurdissima ("most insane and absurd reasoning"), derisione dignas naenias ("screeds worthy of derision"), etc. The modern edition of this text, by Ann Freeman and Paul Meyvaert (Hannover 1998), is called Opus Caroli regis contra synodum ("The work of King Charles against the Synod"), and is based on the manuscript in the Vatican Library, which is now generally accepted as a Carolingian working manuscript "hastily finished up", when it became clear that the work was now redundant.
When the work resurfaced during the Protestant Reformation, it caused a good deal of excitement and confusion, and is for example referred to approvingly but misleadingly by John Calvin in later editions of his Institutes of the Christian Religion (Book 1, Ch 11, section 14), who takes the text at face value.
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