Marie de France's identity remains obscure, but it is clear that she was a woman of French origin writing in England in the later decades of the twelfth century, widely educated, and in touch with the royal court. She dedicates her book of Lais to a "noble King" who was probably Henry II, and she may have been his kinswoman, possibly an illegitimate half-sister. Marie's works draw into that courtly culture the languages and traditions of the English and Celtic past. She rewrote a Latin narrative about the origin of "Saint Patrick's Purgatory" and the adventure of an Irish knight there; and she retold the fables of Aesop using an English translation that she attributed to King Alfred. The Lais, she says, came to her through oral transmission, and she connects them with the Bretons.

Writing a generation after Geoffrey of Monmouth and not long before Gerald of Wales, Marie brings a quite different and rather critical set of preoccupations to her Arthurian story. She opens her tale with a realistic and admirable occasion of male power and strong kingship: Arthur's battle for territory and his reward of faithful vassals. A bleaker side of that courtly world, and perhaps of Marie's own, is also implicit, however. With a terseness and indirection typical of her lais, Marie shows women as property in the king's gift, knights forgotten when their wealth runs out, and the perversion of judicial process. It’s worth comparing the world of Lanval with what we saw in Old English poetry of the relation of lord and retainers, and the connections between men and women.

Marvels and erotic desire dominate her tale, though, and women's power, for good or ill, is its primary motivating force. Guinevere, in a hostile portrait of adulterous aggression and vengeful dishonesty, nonetheless manages to manipulate Arthur and his legal codes when Lanval rejects her advances. The queen is countered by Lanval's supernatural mistress, who commands luxurious riches that dwarf Arthur's; she rescues Lanval by being an unimpeachable legal witness in his defense. Indeed, she arrives on her white palfrey as the moment of judgment nears, almost like a knightly champion in a trial by battle. In a total reversal of convention, once she frees her love, she rides off with him into the sunset—only it’s the man on the back of the horse. Lanval vanishes into a timeless world of fulfilled desire and limitless wealth that has analogies in much older Celtic tradition. This closing scene defies the reintegration of male courtly order that is typical even in the erotic romances of Marie's contemporary Chrétien de Troyes.

The realm of eroticism and women's power in Lanval, though, is not automatically any more virtuous or stable than the ostentatious wealth and corruptible law of the world of Arthurian men. If Lanval's mysterious lady is beautiful and generous, she also takes his knightliness from him. Lanval is last seen riding behind the lady, and not on a warhorse but on a palfrey. Guinevere swiftly reduces Arthur to a weak and temporizing king. And in her initial explosion after Lanval rejects her, Guinevere accuses him of homosexuality. For all its absurdity, the moment articulates unnerving implications of the profound bonds among men in the Arthurian world, implications that could interrupt genealogical transmission of wealth and power. Marie's Guinevere again voices fears the tradition has left unsaid.

Marie de France may be trying less to propound a critique of the received stories of Arthur than to recall her readers' attention to elements that tradition has left aside, as she suggests in her prologue. Some of this is no more troubling than a delightful fantasy of wealth and pleasure, outside time and without consequences. Other elements imply, with startling economy, forces that (in the hands of later romancers) tear the Arthurian world to pieces.

This is only one of Marie’s dozen lais; the others in her collection (including one on the Tristan legend) view love from other points of view, rendering a very kaleidoscopic picture of the relationships of men and women, of individuals and society, and of power and authority in her time.

Sources: http://occawlonline.pearsoned.com/bookbind/pubbooks/damrosch_awl/chapter2/medialib/defrance.html  

http://mockingbird.creighton.edu/english/fajardo/teaching/eng340/marie_de_france.htm  

If you want to read two of Marie's Fables, which seem to anticipate Chaucer's fabliaux, you can find them on the Harvard Chaucer pages at http://www.courses.fas.harvard.edu/~chaucer/special/litsubs/fabliaux/mari-fab.html

Bullet points adapted from http://gondolin.hist.liv.ac.uk/~azaroth/university/orfeo/node13.html  

International Marie de France society: http://www.people.vcu.edu/~cmarecha/

The Lais online: http://www.english.ufl.edu/exemplaria/intro.html

Paul Brians' Marie de France study guide: http://www.wsu.edu/~brians/love-in-the-arts/marie.html