Institutio Oratoria

But the chief fault lies with our teachers, in that they love to keep back the pupils they have managed to lay their hands on, partly from the desire to draw their miserable fees for as long as possible, partly out of ostentation, to enhance the difficulty of acquiring the knowledge which they promise to impart, and to some extent owing to their ignorance or carelessness in teaching. The next most serious fault lies in ourselves, who think it better to linger over what we have learned

than to learn what we do not yet know.