Lorenzo Valla's Discourse on the Forgery of the Alleged Donation of Constantine (1440) demonstrated on philological grounds that the document, claiming Constantine transferred imperial authority over the West to Sylvester I (pope 314-335), could not be ancient: anachronistic Latin, references to Constantinople before it existed, institutions that postdate Constantine. The Donation had been cited since the 11th century in papal-imperial disputes, embedded in Gratian's Decretum (c. 1140). Modern scholarship dates the forgery to the 8th century, the era of papal-Frankish alliance.
The afterlife is the lesson: Valla's exposure circulated in print (1517) and was weaponized by Protestants, yet the papal states, partly justified by the Donation, persisted until 1870. Documentary truth and political fact ran on separate tracks for four more centuries.
The Donation is the archive's purest case of a forged instrument founding real power: a text produced by an institution, for an institution, validated by the institution's own libraries. Every later allegation of foundational forgery, from the Protocols to modern trust-law myths, replays its structure with worse scholarship and no Valla.
If the founding document was forged, what does that make the six centuries built on it?