This study explores the meaning of Michelangelo’s incomplete signature on his marble Vatican Pietà, and the function of the strap on which it is written. His use of faciebat, or ‘was making’, as the imperfect tense of the Latin for facio, implies that his carving was incomplete, or non finito. I argue that completion for Michelangelo meant viewing of the work by an audience, particularly the patron of the carving. The work of art has a content that the viewer must interpret to give meaning to the object. Contemporary authorities are cited for various interpretations of the faciebat signature, as well as comments by artists, ancient writings on oratory, rhetorical devices, and modern analyses of artists’ cognitive engineering. Examples of related art include Benvenuto Cellini’s Perseus, and Bronzino’s Pygmalion and Galatea.

I suggest that Michelangelo’s lone signature was requested by the patron of the sculpture as hinted by Vasari, and that the strap bearing the signature functions as a counterpart to the painter’s apostrophic figure recommended by Alberti. The strap is not part of the Virgin’s costume, and so refers to the bindings used to remove the corpus of Christ from the cross. I conclude that the Pietà that Michelangelo ‘was making’ would have been completed on delivery to its patron, as indicated by Alberti in his Momus, but as the cardinal died before its completion, Michelangelo left the requested signature, facieba[t], incomplete.