In 1401, Brunelleschi entered a competition to design a new set of bronze doors for the Florence Baptistery. Seven competitors each produced a gilded bronze panel, depicting the Sacrifice of Isaac. Brunelleschi's entry, which, with that of Lorenzo Ghiberti, is one of only two to have survived, made reference to the Greco-Roman Boy with Thorn, whilst Ghiberti used a naked torso in the Classical style for his figure of Isaac. In 1403, Ghiberti was announced the victor, largely because of his superior technical skill: his panel showed a more sophisticated knowledge of bronze-casting being cast as a single piece. Brunelleschi's panel, by contrast, consisted of several pieces bolted to the back plate. Ghiberti went on to complete a second set of bronze doors for the baptistery, whose beauty Michelangeloextolled a hundred years later, saying "surely these must be the "Gates of Paradise".