Lorenzo Valla subjects the Donation of Constantine to close linguistic, legal, and historical analysis, arguing that the purported imperial grant is a medieval forgery. He marshals evidence from anachronistic vocabulary, stylistic and formulaic irregularities, and contradictions with administrative and chronological facts to undermine the document's authenticity. The treatise assesses the document's role in justifying papal temporal claims and outlines the political consequences of its exposure. It also demonstrates early internal-critical methods, using word usage and contextual inconsistency as tools for evaluating historical texts.