Institutio Oratoria

The man who pores over every page even though it be wholly unworthy of reading, is capable of devoting his attention to the investigation of old wives' tales. And yet the commentaries of teachers of literature are full of such encumbrances to learning and strangely unfamiliar to their own authors.

It is, for instance, recorded that Didymus, who was unsurpassed for the number of books which he wrote, on one occasion objected to some story as being absurd, whereupon one of his own books was produced which contained the story in question.