Plato, Laws 700c

εἰς ἄλλο καταχρῆσθαι μέλους εἶδος· τὸ δὲ κῦρος τούτων γνῶναί τε καὶ ἅμα γνόντα δικάσαι, ζημιοῦν τε αὖ τὸν μὴ πειθόμενον, οὐ σῦριγξ ἦν οὐδέ τινες ἄμουσοι βοαὶ πλήθους, καθάπερ τὰ νῦν, οὐδʼ αὖ κρότοι ἐπαίνους ἀποδιδόντες, ἀλλὰ τοῖς μὲν γεγονόσι περὶ παίδευσιν δεδογμένον ἀκούειν ἦν αὐτοῖς μετὰ σιγῆς διὰ τέλους, παισὶ δὲ καὶ παιδαγωγοῖς καὶ τῷ πλείστῳ ὄχλῳ ῥάβδου κοσμούσης ἡ νουθέτησις ἐγίγνετο.

The authority whose duty it was to know these regulations, and, when known, to apply them in its judgments and to penalize the disobedient, was not a pipe nor, as now, the mob’s unmusical shoutings, nor yet the clappings which mark applause: in place of this, it was a rule made by those in control of education that they themselves should listen throughout in silence, while the children and their ushers and the general crowd were kept in order by the discipline of the rod.