Nicholas I - Proposueramus quidem

Other Emperors used such terms as "We pray," "We request," "We beseech," in addressing the presidents of the Apostolic See, from time to time; but in all cases with equal respect. You, on the contrary, their heirs not in courtesy and reverence but only on the throne, decline to follow them in this question of manners, and use terms like "We require," "We order," "We command " in bidding us to send some of our subjects to you. Unless we are mistaken, we never hitherto can remember such words as "We command you" being addressed to us by you: and never have we known you coming to such irreverence towards the see of blessed Peter, the prince of the Apostles. . . .

Moreover, to such a pitch of fury have you been excited as to do injury to our Latin speech as to call it in your letter "a barbarian and Scythian tongue" . . . The reason why you call it a barbarian tongue is that you do not understand it. Think then how ridiculous it is that you should be called a Roman Emperor, and yet do not know the tongue that Romans speak. . . . Give up then calling yourself a Roman Emperor: for, according to your opinion, they are barbarians over whom you claim to be Emperor.