But then came the question of filling it with sarcophagi and statues.

As early as November 28, 1520, Giulio de' Medici, at that time Cardinal, wrote from the Villa Magliana.

to Buonarroti, addressing him thus: "_Spectabilis vir, amice noster charissime_." He says that he is pleased with the design for the chapel, and with the notion of placing the four tombs in the middle.
Then he proceeds to make some sensible remarks upon the difficulty of getting these huge masses of statuary into the space provided for them.

Michelangelo, as Heath Wilson has pointed out, very slowly acquired the sense of proportion on which technical architecture depends.

His early sketches only show a feeling for mass and picturesque effect, and a strong inclination to subordinate the building to sculpture.
It may be questioned who were the four Medici for whom these tombs were intended.