Quite enough has been said here about the art of painting. It is now time to say something about modelling. By taking advantage of the earth itself, Butades, a potter from Sicyon, was the first to introduce the modelling of portraits in clay at Corinth. This was thanks to his daughter. She was in love with a young man, and when he was going abroad she drew a silhouette on the wall round the shadow of his face cast by the lamp. Her father pressed clay on this to make a relief and fired it with the rest of his pottery. This is said to have been preserved in the shrine of the Nymphs until Mummius sacked Corinth.
--Pliny the Elder, Natural History, Book XXXV
Vitaly Komar and Alexander Melamid, The Origins of Socialist Realism (1983), Zimmerli Art Museum at Rutgers University.