The tradition was carried on in Italy at Ravenna and Venice, where the _Opus Miserum_ reached its culmination. Of the Ravenna mosaics, those of the Baptistery, A.D. 450, and of S. Apollinare are typical examples of the earlier Byzantine mosaics, having dark green and gold back-grounds with tesseræ about 3/8 inch square. The beautiful frieze of male and female saints in S. Apollinare extends along both sides of the nave, and is 10 feet high. The vaulting and domes of St. Mark are entirely covered with the characteristic 11th century Byzantine gold ground mosaic, formed by fusing two pieces of glass together with gold leaf between. At Santa Sophia, Constantinople, other fine mosaics exist of the 6th and 7th centuries. In Italy under the Cosmati (a family of mosaicists of the 13th and 14th centuries), fine geometrical inlaid mosaics were used for the enrichment of marble tombs and altars; some good examples of this style are in Westminster Abbey on the tomb of Edward the Confessor (finished under Henry III, A.D. 1270). [Illustration: GREEK CERAMICS. Plate 27. ] GREEK CERAMICS. It is difficult in the 19th century to realise the importance of vases in ancient life. To the Greeks a vase was a receptacle for food, liquid, or storage, and for the adornment of the home. It was used in the daily life of the living and buried with the dead. Most of the finer Greek vases have been found in Etruscan tombs, but of Greek workmanship, imported from Greece or Grecian Colonies. Some black unglazed Etruscan vases have been found, but painted vases of Etruscan origin are rare.