Michelangelo, riding on a mule, watches the Taddeo Zuccaro painting the facade of Palazzo Mattei in Rome, guided by graces

Inscription: from the artist’s hand on the horse-cover “Michelangelo B.rota’; below the painter on the house wall” Thaddeo Zuccaro’; on the sun plaque “grazie B..” (?); on the cornice below “Taddeo Zuccaro fece..”;