This date is fixed by a passage in Pliny.[323] According to him, its introduction was due to Pamphilos the Macedonian. At his instance, first at Sikuon, where he lived, and afterwards in the rest of Hellas, free boys were taught before everything painting on boxwood, and this art was included in the first rank of the liberal arts. Now Pamphilos’ picture of the Herakleidai is mentioned in the _Ploutos_ of Aristophanes, which appeared in 388 B.C. Apelles, his pupil, began to come into prominence about 350: Pamphilos himself seems to have lived on till the close of the century. The introduction of painting into the schools at Sikuon may therefore be dated, roughly, about 360 B.C., and from there the custom spread over Hellas. By 300 B.C. no doubt art had become a regular part of the educational curriculum; for the philosopher Teles,[324] who probably lived about that time, mentions the gymnastic trainer, the letter-master, the musician, and the painter as the four chief burdens of boys. A trace of the new art-schools, with their technical vocabulary, is found in the _Laws_, the work of Plato’s old age:[325] “paint in or shade off,” he says, “or whatever the artists’ boys call it.” Of the methods used in drawing and painting in Hellas little trace is left. Polugnotos and his contemporaries had produced idealised pictures, taking points from many beautiful men and women and uniting them to make one perfect man or woman. When Idealism gave way to Realism in Hellas, the change affected painting also. The artists tried to create a real illusion in their works, taking subjects like chairs or tables and making the spectator believe them to be real. They were helped by the developments of perspective and foreshortening, which were discovered at this time. It is against this exaggerated realism and the choice of homely subjects that Plato’s attack is directed: he hates such illusions as shams.[326] In the diatribes of the _Republic_ the possibility of idealised painting seems to be forgotten. Whether the boys in the art-schools also suffered by this change and were condemned to draw chairs and tables only cannot be decided. The pupils, of course, did not have paper to draw and paint upon, nor was canvas employed. Ordinarily they used white wood, boxwood for preference, owing to its smoothness. Lead or charcoal would serve for drawing; for erasures, instead of india-rubber a sponge was used.[327] They may, perhaps, have practised on their wax tablets. One process was σκιαγραφία [skiagraphia] “shadow-drawing,” which produced rough sketches in light and shade: these seem to have been only intelligible when considered from a distance. Plato regarded them with distrust, as a sort of conjuring.[328]