Marie (since 1581 called "Marie de France" [Lais 7]), "Prologue," lines 9-27, on authors, difficult texts, and readers' interpretive skills

9 custume fu as anc‹ens,
10 ceo tes[ti]moine Prec‹ens,
11 es livres ke jadis feseient
12 assez oscurement diseient
13 pur ceus ki a venir esteient
14 e ki aprendre les deveient,
15 k'i pessent gloser la lettre
16 e de lur sen le surplus mettre.
17 li philesophe le saveient
18 e par eus memes entendeient,
19 cum plus trespasserunt le tens,
20 plus serreient sutil de sens
21 e plus se savreient garder
22 de ceo k'i ert, a trespasser.
23 ki de vice se volt defendre
24 estud‹er deit e entendre
25 e grevos'ovre comencier:
26 par [ceo] se puet plus esloignier
27 e de grant dolur delivrer.

It was customary for the ancients, in the books which they wrote (Priscian testifies to this), to express themselves very obscurely so that those in later generations, who had to learn them, could provide a gloss for the text and put finishing touches in their meaning.  Men of learning were aware of this and their experience had taught them that the more time they spent studying texts the more subtle would be their understanding of them and they would be better able to avoid future mistakes.  Anyone wishing to guard against vice should study intently and undertake a demanding task, whereby one can ward off and rid oneself of great suffering.  (Prose Translation, Glyn Burgess and Keith Busby)

 Among the ancients it was the tradition
(On this point we can quote Priscian)
When they wrote their books in the olden day
What they had to say they'd obscurely say.
They knew that some day others would come
And need to know what they'd written down;
Those future readers would gloss the letter,
Add their own meaning to make the book better.
Those old philosophers, wise and good,
Among themselves they understood
Mankind, in the future tense,
Would develop a subtler sense
Without trespassing to explore
What's in the words, and no more.
Whoever wants to be safe from vice
Should study and learn (heed this advice)
And undertake some difficult labor;
Then trouble is a distant neighbor--
From great sorrows one can escape.  (Verse Translation, Judith Shoaf, http://web.english.ufl.edu/exemplaria/marie/prologue.pdf)

        Readers of Prician (fl. 500 CE) can find no such assertion about ancient authors' intentional obscurity to improve their readers' interpretive skills.  This fact would have been far more widely known in Marie's time than in our own.  Prician's Institutiones grammaticae (before the first quarter of the C6), though somewhat obscure for all but the learned, nevertheless was a standard Latin grammar so synonymous with authority that Cobham Brewer's Dictionary of Phrase and Fable (1898) lists the Latin phrase, "Diminuere Prisciani caput" or "to break Priscian's head" as an idiom for "to make a grammar error."  Any scholar in the court could tell that Marie was bending Priscian's text from its obvious meaning.  What is Marie doing?

        If you want to "ask the oracles," consult Mortimer Donovan, "Priscian and the Obscurity of the Ancients," Speculum 36:1 (January 1961) 75-80. Stable URL: http://www.jstor.org/stable/2849845.  But Professor Donovan interprets Marie, a vernacular French writer, in the context of Latin scholarly writers, and takes no account of how the tales which follow the Preface either do or do not strive to obscure their meaning.  (They do.)  Or you could consult Monica Brzezinski Potkay, "The Parable of the Sower and Obscurity in the Prologue to Marie de France's Lais," Christianity and Literature (22 March 2008), who sees Marie's words as the sower's "seeds" in Jesus parable, some falling fruitless on stony minds, whereas others encounter fertile minds and produce new crops of ideas.  That would make the text's "flower" the reader's response to the text, wouldn't it?