The rude figures of saints at the extremities of the roof, both of the aisles and nave, mark the beginning of that revival of the human figure in sculpture, which was the forerunner of the work of Niccolò Pisano. The tower and Baptistery are the natural results of the Duomo, the style being identical; the same round arches in the foundation, and the same circles of Lombard galleries covering the super-structures. The Baptistery was built by Magister Diotisalvi, somewhere about 1152. We have no proofs of his origin, but his work and title prove him to have graduated in the same guild as Buschetto and Rainaldo,[167] and we find his son and grandsons in Siena and other lodges. In the Baptistery, the old mystic octagonal form was abandoned, and the circle takes its place. Diotisalvi has here made a perfect bell in tone as well as in form. It is the most acoustic building possible, as any one may prove by singing in rotation the notes of a chord. The whole chord echoes on for several moments with exquisite effect. The Baptistery was begun in August 1152, the first stone being laid in the presence of the Consul Cocco di Tacco Grifi; and two of the _Operai_ (members of the administrative council or _Opera_) named Cinetto Cinetti, and Arrigo Cancellieri, were appointed _soprastanti_ (overseers). Here again we have a distinct connection between the _Opera del Duomo_ and the _laborerium_. Some of the classic spoils of war were given to Diotisalvi for this building. Several of the capitals on the twenty columns supporting the foundation circle of round arches, are Corinthian; and the two pillars at the chief portal are beautiful specimens of ancient work, similar to those in the façade of the Duomo. Between the classic remains incorporated into the building, and the statues and sculptures which belong to a later century, it is difficult to distinguish which were the absolute work of Diotisalvi himself. The sculptures on the door-jambs--rather mediæval scenes relating to Christ and David--and the hieroglyphics of the months were probably his own work. The Baptism of Christ on the architrave, which has the mediæval expression of baptism by immersion, may be his; and if so, it seems to explain how the Greek element got into Niccolò di Pisa's work, for here is his antecedent of a century, showing in his work signs of the same leaning to classicism in the midst of a rude and early style. How could he help it when he was living among classic remains of sculpture?