The Donation of Constantine (Latin, Donatio Constantini) is a forged Roman imperial decree by which the emperor Constantine the Great  supposedly transferred authority over Rome and the western part of the Roman Empire to the Pope. Composed probably in the 8th century, it was used, especially in the 13th century, in support of claims of political authority by the papacy. Lorenzo Valla, an Italian Catholic priest and Renaissance humanist, is credited with first exposing the forgery with solid philological arguments in 1439–1440, although the document's authenticity had been repeatedly contested since 1001.
In many manuscripts, including the oldest one, the document bears the title 'Constitutum domini Constantini imperatoris'.
Lorenzo Valla, in 'De falso credita et ementita Constantini donatione declamatio', proved the forgery with certainty. This was the first instance of modern, scientific diplomatics. Independently of both Cusa and Valla, Reginald Pecocke, Bishop of Chichester (1450–57), reached a similar conclusion. Among the indications that the Donation must be a fake are its language and the fact that, while certain imperial-era formulas are used in the text, some of the Latin in the document could not have been written in the fourth century; anachronistic terms such as "fief" were used. Also, the purported date of the document is inconsistent with the content of the document itself, as it refers both to the fourth consulate of Constantine (315) as well as the consulate of Gallicanus (317).
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