Dante, Botticelli, and Trajan. An Open Note

In his illustration for Canto X of Purgatory, Sandro Botticelli draws the legendary episode of the Justice of Trajan. In order to illustrate the legend, Botticelli apparently takes inspiration from the bas-relief in the fornix of the Arch of Constantine with the inscription liberatori urbis, a bas-relief that, thanks to modern archaeological studies, is known to come from a monument of Trajan. In the Note here published, we question how Botticelli could have known the Trajanian origin of the bas-relief. The analysis is carried on by surveying all the sources available at the time and the critical studies. At this stage of the research, the conclusion that could be reached is that the identification of the bas-relief as pertaining to a Trajanian monument might have derived from a vox populi.