This analysis of Giorgio Vasari’s 1568 addendum to the vita of Leonardo explores Vasari’s rhetorical and narrative strategies to dramatize the importance of both visual artist and patron’s possessing l’intelletto d’arte—“the intelligence of art.” A close reading of Vasari’s tale about Leonardo and the Duke of Milan leads to new interpretive avenues, which reveal how Vasari prioritized his own competing values within a rhetorical program. He uses his supplemental raccontino for a sophisticated discussion of art: in this discourse between Leonardo and his patron, Vasari stages an epistemological debate. He fills his narrative with subplots to emphasize the moral contrast between Christ and Judas in the Last Supper. Focusing on an ethical interpretation of style, Vasari presents Leonardo’s good character and artistic intelligence as the sources of the beauty and achievement found in the cenacolo. Building on a comprehensive system of artistic best practices, this narrative parallels the pursuit of an ideal concept of collective good that is nourished by Vasari’s poetic generosity.