Two apostolic nuncios, stationed, the one at Constantinople, the other at Ravenna, offered to the emperor and to the exarch the respect, devotion, and tribute of the Roman pontiff. Pope Leo II. towards the year 683, writing to Constantine Pogonat, calls him his king and lord.²² In 686 and 687, the elections of the popes Conon and Sergius were confirmed, the one by the Exarch Theodoric, the other by the Exarch Platys, who exacted from Sergius a large sum, although this description of tribute had been abolished by the Emperor under the pontificate of Agathon.²³ ²⁰ Morin. History of the Origin and Progress of the Power of the Popes, p. 664, ²¹ Fleury. Ecclesiastical Hist. b. 39, n. 33. ²² Morin. History of the Origin and Progress of the Power of the Popes, p. 664. ²³ Anast. Hist de vit. Bom. Pont, pages 147, 149. In 710 Pope Constantine, ordered to Constantinople by Justinian the Second, hastened to obey this superior order.²⁴ We shall only cite a letter written by the Pontiff to the Duke of Venice in 727:²⁵ “The city of Ravenna having been taken, because “of our sins, by the wicked nation of the Lombards, “and our excellent master, the Exarch, being, as “we are informed, retired to Venice, we conjure “your Highness to unite with him, in order to re− “store the city of Ravenna to the imperial domi− “nion; to the end that we may, by the Lord’s as− “sistance, remain inviolably attached to Leo and “Constantine, our august emperors.” The Pope who thus expresses himself, is Gregory the Second, one of those who may be suspected of having been amongst the first, who sought to extend, beyond the bounds of the apostolat, the pontifical authority. His letter at least proves that the imperial sovereignty was then a right universally acknowledged; a public and undeniable fact. It is however in the eighth century, and a short time after the date of this epistle, that we perceive, not the establishment certainly, but the first symptoms of the temporal power of the Roman prelates. The various causes which could tend to this result, about this period begin to be perceptible, and to acquire additional strength from their combined operation. ²⁴ Fleury. Ecclesiastical Hist. b. 41, no. 22. ²⁵ Baronius. Ecclesiastical Annals, vol. 13, p. 343.