It may be questioned who were the four Medici for whom these tombs were intended. Cambi, in a passage quoted above, writing at the end of March 1520(?), says that two were raised for Giuliano, Duke of Nemours, and Lorenzo, Duke of Urbino, and that the Cardinal meant one to be for himself. The fourth he does not speak about. It has been conjectured that Lorenzo the Magnificent and his brother Giuliano, fathers respectively of Leo and of Clement, were to occupy two of the sarcophagi; and also, with greater probability, that the two Popes, Leo and Clement, were associated with the Dukes.
Before 1524 the scheme expanded, and settled into a more definite shape. The sarcophagi were to support statue-portraits of the Dukes and Popes, with Lorenzo the Magnificent and his brother Giuliano. At their base, upon the ground, were to repose six rivers, two for each tomb, showing that each sepulchre would have held two figures. The rivers were perhaps Arno, Tiber, Metauro, Po, Taro, and Ticino. This we gather from a letter written to Michelangelo on the 23rd of May in that year. Michelangelo made designs to meet this plan, but whether the tombs were still detached from the wall does not appear. Standing inside the sacristy, it seems impossible that six statue-portraits and six river-gods on anything like a grand scale could have been crowded into the space, especially when we remember that there was to be an altar, with other objects described as ornaments--"gli altri ornamenti." Probably the Madonna and Child, with SS. Cosimo and Damiano, now extant in the chapel, formed an integral part of the successive schemes.
One thing is certain, that the notion of placing the tombs in the middle of the sacristy was soon abandoned. All the marble panelling, pilasters, niches, and so forth, which at present clothe the walls and dominate the architectural effect, are clearly planned for mural monuments. A rude sketch preserved in the Uffizi throws some light upon the intermediate stages of the scheme. It is incomplete, and was not finally adopted; but we see in it one of the four sides of the chapel, divided vertically above into three compartments, the middle being occupied by a Madonna, the two at the sides filled in with bas-reliefs. At the base, on sarcophagi or _cassoni_, recline two nude male figures. The space between these and the upper compartments seems to have been reserved for allegorical figures, since a colossal naked boy, ludicrously out of scale with the architecture and the recumbent figures, has been hastily sketched in. In architectural proportion and sculpturesque conception this design is very poor. It has the merit, however, of indicating a moment in the evolution of the project when the mural scheme had been adopted. The decorative details which surmount the composition confirm the feeling every one must have, that, in their present state, the architecture of the Medicean monuments remains imperfect.