 Caesar Baronius, who drafted a new edition to the "Roman Martyrology" (1586), doubted the veracity of the tale.In the twentieth century, the historian Aimé Pierre Frutaz demonstrated that the "Magna Legenda Sancti Grati" was an invented tale.However, the tale had spurred the diffusion of Gratus' cult into Piedmont, Lombardy, Switzerland and Savoy, and provided the basis for the saint's attributes.