Vanity gets a bad rap in popular folklore: from Cinderella to The Devil Wears Prada, the bad girls are usually the vain, superficial, and ultimately unhappy counterparts to the heroine’s modest, unassuming persona.

This aspect of storytelling – and the miniatures that illustrate it – play an integral part in a new exhibition at The Morgan Library and Museum in New York. Illuminating Fashion: Dress in the Art of Medieval France and the Netherlands tours the history of medieval dress in the best preserved records available: illuminated manuscripts and books from the period. While most of the garments worn during that time are gone, many hand-illustrated books and manuscripts have survived in private collections. These books include Bibles and many Books of Hours (a prayer book  that was often specially commissioned for its reader), as well as popular literature and treatises on the proper way to go about courtly life.

While most of the religious figures in the books are portrayed in older, classical dress, the lay people in the stories are illustrated in current-day fashions. Lovers of historical dress will marvel over the detail artists included in these illustrations. They gives us a window into the fashions of the day – as well as the social mores regarding dress and vanity. For amid the treatises regarding courtly life and hunting, there are also famous morality tales, in which those taking the moral low road are decked out in finery.

Above is an illustration of Fortune and Poverty meeting at the crossroads, from Boccaccio’s Of Noble Men and Women. (Detailed photo with zoom .) Fortune is beautifully attired, with a tall turret (headdress) and gossamer veil, and an ermine-trimmed gown of luscious fabric. Poverty is in rags, with the Cross backing her up. She is portrayed as a pious religious pilgrim (though apparently not so pious she won’t beat the stuffing out of Fortune!)

And there’s Delilah (Detailed photo ) – a Biblical bad girl, looking good as she destroys her man. While she doesn’t display the same wealth as Fortune, she is attired in the latest fashion, with a high belt and a touch of ermine trimming her neckline. And her hairstyle is huge: the horns of her hairstyle are broader than her shoulders, an ironic touch for the woman cutting off Samson’s hair.

This isn’t just about women – men get theirs as well. In Bible scenes, Jesus is never shown in fancy clothes, but his male tormentors are generally portrayed wearing the latest fashions.

Certainly, these tales exist to warn their readers from excluding inner virtues, but why the hating on looking good? Perhaps it is because many illustrators were monks and nuns, whose own vows of poverty served them well in encouraging others to not be so vain. By highlighting the contrast between good modesty and bad vanity, the illustrators may have been warning their affluent readers away from excess. And visually, there’s got to be contrast between good and evil, just to help the story along.

There are exceptions to this rule: commissioned portraits show their patrons at their best – both morally and sartorially. Here is Catherine of Cleves, portrayed in her personal Book of Hours, giving alms in a beautifully detailed ensemble. (Detailed photo .) She is wearing lots of jewelry, an elaborate hairstyle, and an ermine lined, scarlet houpeland – portraying the ideal elegant, wealthy, dutifully charitable royal.

Which isn’t so far from our own fairy tales – Cinderella does, after all, get her own gorgeous ensemble (and a prince!) And there’s a makeover scene in almost every fashion-as-evil-empire movie/TV show out there. And maybe that’s what drives these stories: we want to be the modest, good people we certainly are, yet still get to wear fabulous clothes.

Certainly the human personality hasn’t changed that much since Medieval times, though we now live in a culture that is affluent and diversified enough to support its most purely vain and superficial citizens quite well. Perhaps, like the Medieval royals these books and manuscripts were illuminated for, we need this contrast between the extremes of vanity to help sort out what in these portrayals is vital to our own personae – and to find a way to navigate the complexities of life in an affluent society.

Illuminating Fashion: Dress in the Art of Medieval France and the Netherlands
through September 4, 2011 at The Morgan Library and Museum