It's noteworthy how teachers were paid 'by the pupil'
Indeed, the Roman author Quintilian held teachers who insisted on small class-sizes in contempt, as mere "pedagogues" (by etymology, slaves who baby-sat children), and insisted that a skilled teacher could handle a large class by his rhetorical power.
I've seen that difference up close, we had a math teacher in high school that was a fairly small, unassuming little guy. But he radiated a fair amount of power and whenever he lectured you could have heard a pin drop in the pauses. The year after we got one of the 'pedagogues', the grade point average dropped right through the floor and pandemonium was more likely than order. Same kids... what a difference.
Indeed, the Roman author Quintilian held teachers who insisted on small class-sizes in contempt, as mere "pedagogues" (by etymology, slaves who baby-sat children), and insisted that a skilled teacher could handle a large class by his rhetorical power.