"Marble Madonna"

In Marble Madonna Donatello's brilliant handling the very shallow relief carving technique called flattened relief (rilievo schiacciato), a technique which he invented,is displayed.  Using the technique he  could create the illusion of volumetric forms set into deep, continuous space with the most subtle and shallow carving. Art critics have said that  Donatello handled his chisel almost like a paint brush, creating a series of rippling modulation for catching the light from different angles, andthis gives the illusion of volume even though the actual depth of the carving can be measured in millimeters.