Only once did Michelangelo sign a sculpture. It was the ‘Pietà’ of 1497–1500, and he did so using an incomplete sentence in the past imperfect: ‘Michelangelo Buonarroti the Florentine was making…’. The implication was that actually completing a perfect masterpiece was an unattainable goal, so instead he just had to leave off (a great many artists still feel the same about finishing a picture).