Julius II's decision to completely renovate the decoration of the ceiling was probably due to the serious structural problems that affected the Sistine Chapel from the earliest years of his pontificate (1503-1513). On 8 May 1508 Michelangelo signed the contract which foresaw the painting of twelve apostles in the pendentives and ornamental motifs in the rest. Subsequently, at the request of Buonarotti himself, who considered the project to be a "poor thing", the Pope gave him a new commission in which he left the full planning of the programme to the artist. It is however quite likely that for his creation the artist sought the cooperation of the theologians of the papal court. Michelangelo placed nine central stories illustrating episodes from Genesis within a powerful painted architecture, with at their sides figures of nudes, holding medallions with scenes taken from the Book of Kings. At the base of the architectural structure twelve prophets and sibyls seated on monumental thrones contrast with Christ's forefathers, portrayed in the spandrels and in the lunettes below. Finally, in the four corner pendentives, the artist illustrated some episodes of the miraculous salvation of the people of Israel. In August 1510 Michelangelo completed the first half of the ceiling from the entrance wall to the Creation of Eve. The work was most likely completed by 31 October 1512 since the Pope celebrated Mass in the Chapel on 1 November.