Giorgio Vasari

“ The people of Bologna had been fully convinced that it was not possible to execute a work in marble which should surpass, or even equal, that which Agostino and Agnolo, of Siena, had produced in the high altar of San Francesco, in their city, a work in the old manner; they were infinitely surprised, therefore, on perceiving that this was very far superior. Having completed this undertaking, and being requested to return to Lucca, Jacopo repaired thither very willingly, and in the church of San Friano, of that city, he executed an altar-table of marble for Federigo di Maestro Trenta del Veglia. ”

“ The whole of the work is equally full of admirable qualities, exhibiting judicious consideration and much discernment throughout; beautiful children and other ornaments, with lions and wolves, which belong to the arms of Siena, form its decorations; the whole being completed by the practised hand of Jacopo with infinite judgment, devotion, and diligence, in the space of twelve years. Three very beautiful stories, in bronze, representing events from the life of St. John the Baptist, in mezzo-rilievo, are also by this sculptor. ”

“ The sculptor Jacopo, son of Maestro Piero di Filippo of Quercia, a place in the neighbourhood of Siena, was the first —after Andrea Pisano, Orgagna, and the other masters above named—who, devoting himself to sculpture with a more earnest study, began to show that a near approach might be made to Nature herself ”