Cranach's imaginary harem survives more or less intact, albeit much dispersed and somewhat altered by conditions of modern museum display. The majority of his slender and doe-eyed temptresses were originally devised for the delectation of a single owner in a private room. Now they proposition the general public. Several of them may be found doing just that in the modest exhibition of a dozen or so Cranachs currently at the National Gallery in London.
To borrow a phrase from the great art historian Erwin Panofsky, Cranach was "the very model of a major minor master". He was no pioneer. His Italian contemporaries, Titian and Giorgione, preceded him in depictions of the naked Venus (the issue of precedence apart, Cranach never did paint a picture to rival Giorgione's Sleeping Venus in Dresden or Titian's Venus of Urbino in the Uffizi). But he was certainly the first northern European artist to understand that the Renaissance revival of interest in classical subject matter provided painters with a licence for the manufacture of erotic art. His chief invention, the Cranach nude, is more original and interesting than she is generally made out to be.
She is instantly recognisable because, although she might wear many mythological disguises, she is always the same woman - or at least, for there is not too much reality about her, the same dream of one. Sometimes she pretends to be Venus, sometimes Eve. Sometimes she travels incognito, as a water nymph. Sometimes, with a sly, knowing expression on her face, acknowledging the imposture even as she plays the role, she impersonates Lucretia, sword in hand, nobly insisting that she prefers suicide to the loss of her honour. But we know it is not true, and she knows that we know. Her dissembled chasteness is as transparent as the gauzy wisp of drapery she often clutches to her, like Salome down to her very last veil.
There is something doll-like about the Cranach girl, and something troublingly childish about her, too. A fille fatale with bedroom eyes, she is a Renaissance Lolita. Cranach was so attached to this dream creature that he probably could not have varied her had he tried; even when we see three naked goddesses in one picture, they actually turn out to be the same one figure multiplied. The National Gallery's exhibition includes a woodcut, The Judgement of Paris, in which we see Venus, Athena and Juno showing off their charms to a sleepy and grizzled knight in a chilly alpine landscape. They are so similar to one another (almost identical, in fact, despite tiny differences in hairstyle and jewellery) that Paris's task seems quite impossible. The subject is clearly a pretext for showing the same girl from three angles - front, back and side. It is a way of giving her more completely to the viewer, as if she were a figurine to be turned this way and that in the hands.
Cranach was in many respects the epitome of the German 16th-century painter, following in the wake of Italian innovations, yet unwilling or unable to abandon the northern Gothic traditions in which he had been trained. The slightly disconcerting, pubescent character of his ideal girl owes at least something to that tradition. Cranach might have followed the artists of the Italian Renaissance in adopting the subject matter of classical myth, but his visual imagination remained stubbornly northern European. So the Cranach girl bears no relation to Titian's ripe Venuses. With her small head, her narrow, sloping shoulders and her long legs, she is a neo-Gothic creature - a direct descendant of the naked Eve painted by the Limbourg brothers in their celebrated illuminated manuscript for the Duc de Berry, the Tres Riches Heures.
Cranach's ingenuity in making this quintessentially sexless figure seem sexy should not be underestimated. He does it partly through the poses which he has her adopt, partly through the expression which he puts on her face (self-possessed, inviting, orientally languorous), and partly through the way in which he clothes her with such conspicuous inadequacy. She is hardly ever entirely nude, but the few bits and pieces that she does wear - she has a marked fondness, in particular, for bejewelled chokers and extravagant broad-brimmed hats - make her look even more undressed than if she were stark naked.
Having started his career as a painter of religious subjects, Cranach continued to produce altarpieces and devotional panels - albeit of increasing feebleness - until the very end of his life. He had always been, and always remained, an extremely competent and prolific painter of grave, quiet, highly realised portraits, very much in the northern European tradition. He did not only paint Eves and Venuses and Lucretias, in other words. But he did paint enough of them to have been damned, for ever, as a fundamentally trivial artist: a man who sold his soul and became a mere lackey to the decadent tastes of the court he served, a painter whose works, in Max Friedlander's words, "are immediately recognisable and invariably elicit a fleeting, superior smile".
There is some truth to this. Few would argue that compared to Italian Renaissance contemporaries such as Raphael and Michelangelo, or indeed compared to his closest friend in Wittenberg, that most fervent of early Protestant reformers, Martin Luther, Cranach was indeed something of a lightweight. But the dream enshrined by that curious, waif-like ideal girl, the Cranach nude, was still very much a dream of its time - and it was just as much a dream of renewal, in its own sexy way, as Raphael's dream of reviving the grand lost world of classical antiquity or Luther's dream of reviving the pure true faith of early Christianity. The universal fantasy of going back, of returning to some original, unblemished state could take many forms in the first half of the 16th century.
Cranach explained this, so to speak, in one of his last and best mythologies, a picture based on the ancient theme of The Fountain of Youth (not included in the National Gallery exhibition; it is to be found in the Gemaldegalerie in Berlin). The fountain in question is envisaged, by the painter, more like a swimming pool. A mass of old women huddle to one side, awaiting their turn in the magic waters; the pool itself is full of laughing, splashing figures. Those who step out, having bathed, have been restored to nubile youth and beauty. They have become, in short, Cranach nudes. The picture is certainly quaint, but it has its own emotional intensity and, as the work of a very old man (Cranach painted it in 1546), may contain an element of autobiographical confession. It is, perhaps, a kind of coda to all his other mythologies, an account of what the ideal girl had represented all along - a fantasy not of sex, pure and simple, but of being remade as good as new, a sensual dream of rebirth, rinascita, Renaissance.
`Cranach: A Closer Look': National Gallery, Trafalgar Square, London WC2 (0171-839 3321). To 7 Sept