Institutio Oratoria

Suppose we are given a pupil who, like so many, is of depraved tastes and swollen with his own conceit; shall we suffer him to go his own sweet way? If a boy's disposition is naturally dry and jejune, ought we not to feed it up or at any rate clothe it in fairer apparel? For, if in some cases it is necessary to remove certain qualities, surely there are others where we may be permitted to add what is lacking.

Not that I would set myself against the will of nature. No innate good quality should be neglected, but defects must be made good and weaknesses made strong.