We owe our knowledge of Greek sculpture history to the existence of casts, a technology that has allowed us to keep the plaster moulds of sculptures. By copying Greek statutes, a reliable standard has been set. The issue of the reproducibility of a work of art is examined from a historical and technological perspective (printing of images, engraving, the photography revolution of the 19th century and the invention of cinematography in the 20th century). The author finally examines the crucial step from the analogue to the digital technology. The history of copies is the ability to define standards and impose models. In particular, the author analyses two recent examples. The digital reproduction of the "Cena" by Paolo Veronese, a large work of art which was set up where the original was once kept (at the Louvre) in the refectory of the San Giorgio Convent in Venice, and Peter Greenaway's work on the digital reproduction of Leonardo's masterpiece, "The Last Supper" at Palazzo Reale.