The continuity of Greek and medieval art was assured by the 
bond between caelatura or engraving and illumination.

*     In his Approach to Greek Art  (p. 43) Charles Seltman 
writes:

     The Greeks had no paper: papyrus was expensive, 
     reserved for documents and unsuitable for drawing. Wax 
     tablets had no permanence. In fact, the surface of the 
     vase was the drawing-paper of the artist. . . . It is 
     significant that from 650 B.C. onwards Athenian potters 
     had already established a big export trade and were 
     sending their products overseas to Aegina, Italy, and the 
     East.

     Seltman in this passage indicates why the Greeks made so