Giuseppe Moletti (1531-1588) is now remembered only as one of the mathematicians to whom a young Galileo submitted some theorems on centers of gravity, and as Galileo's immediate predecessor in the chair of mathematics at the University of Padua. Yet in his day Moletti was well-known and highly regarded: he was, for instance, one of the mathematicians consulted by Pope Gregory on calendar reform, and his geographical and astronomical works went through several editions in his lifetime. Since his death, however, the only writing of Moletti's to be printed was a brief passage that caught the attention of Giambattista Venturi in the early nineteenth century. Venturi, searching for lost fragments of Galileo's works, came upon Moletti's otherwise unknown and unprinted “Dialogue on Mechanics” in a manuscript in the Biblioteca Ambrosiana, Milan.