Tesserae

   Small pieces of stone or glass cut into squares and used to create mosaics. Tesserae of different colors are glued to the wall, ceiling, or floor to form an image or decorative pattern and the spaces between them are then grouted to produce an even surface. This method was devised in the ancient era to decorate interior domestic and public spaces with mythological or political scenes. With the adoption of Christianity as the official faith of the Roman Empire, the subjects of the mosaics changed from mythological to religious. Brilliantly colored tesserae were applied to the wall surfaces of churches to create images that awed the faithful and instructed them on Christian doctrine. The glitter produced by the tesserae, especially those cut from colored glass, provided a splendorous backdrop for the mass. These types of mosaics continued to be produced well into the Proto-Renaissance era. Examples include Jacopo Torriti's apse mosaics in the Basilica of St. John Lateran (c. 1291) and at Santa Maria Maggiore (c. 1294), Rome, Coppo di Marcovaldo's mosaics covering the vault of the Baptistery of Florence (second half of the 13th century), and Giotto's Navicella, the scene when Christ walks on water to save St. Peter from drowning, once placed in the courtyard façade of Old St. Peter's (c. 1307, destroyed)

   See also Cosmatesque style.