Plato, Laws 720c

ὄντων τῶν καμνόντων ἐν ταῖς πόλεσι, τοὺς μὲν δούλους σχεδόν τι οἱ δοῦλοι τὰ πολλὰ ἰατρεύουσιν περιτρέχοντες καὶ ἐν τοῖς ἰατρείοις περιμένοντες, καὶ οὔτε τινὰ λόγον ἑκάστου πέρι νοσήματος ἑκάστου τῶν οἰκετῶν οὐδεὶς τῶν τοιούτων ἰατρῶν δίδωσιν οὐδʼ ἀποδέχεται, προστάξας δʼ αὐτῷ τὰ δόξαντα ἐξ ἐμπειρίας, ὡς ἀκριβῶς εἰδώς, καθάπερ τύραννος αὐθαδῶς, οἴχεται ἀποπηδήσας πρὸς ἄλλον κάμνοντα οἰκέτην, καὶ ῥᾳστώνην οὕτω τῷ δεσπότῃ παρασκευάζει τῶν καμνόντων

the slaves are usually doctored by slaves, who either run round the town or wait in their surgeries; and not one of these doctors either gives or receives any account of the several ailments of the various domestics, but prescribes for each what he deems right from experience, just as though he had exact knowledge, and with the assurance of an autocrat; then up he jumps and off he rushes to another sick domestic, and thus he relieves his master in his attendance on the sick.