Great Works: Venus (1532), Lucas Cranach the Elder

Stadel Museum, Frankfurt Am Main

The human body is, obviously, the number one subject of European art (and of several other world arts, too). But how few of our body images involve simply the observation and recording of a body. And how many of them involve the radical alteration of a body, indeed the reconstruction of it almost from scratch.

The extremes of plastic surgery are nothing to what art attempts. The body becomes a plaything for outlandish variation. You can see this as the imposition of strict and punishing ideals. Or you can see it as the exercise of wild imagination. In these images we assert our freedom, refuse our physical limits and transform ourselves into something we can never be.

And it's not just that these metamorphoses turn us into something unnaturally strong, gigantic, graceful, beautiful or sexy. When they're performed in a D picture, then the loss of a dimension also lends us an extra dimension of possibility. In the flat, we can design physical marvels. We can visualise bodies that are literally beyond anything that could exist.

There is a body manipulation trick used by fashion magazines. It's a two-stage operation. Stage 1: the model or the star has been dressed all in tight black. This black costume is then filled in – on the page or on the screen – so that it becomes an area of totally uniform blackness, with no modulation of light or shading within it.

The model's body, in other words, has been turned into a flat silhouette. (Black is the colour that it's best to do this with. It's just about believable that all light could have been absorbed into it.) And as in a silhouette, all the information about her body is carried by the outlines of its shape.

This allows for Stage 2. The magazine's art team can get going at reshaping her figure with very little trouble. Simply by altering the outer edges of this silhouette, by cutting away some contour here, or by adding on some there, the woman can be made skinnier or curvier, as editorial pleases, within the limits of plausibility – or usually beyond.

There are more elaborate ways of refashioning a human body. But the simplicity of this method makes its falsifications and impossibilities less easy to detect. It can only be done in a D picture. The trick is not new.

Sometimes we take the old masters as models of sanity, when it comes to imperfect bodies and the ageing process. Rubens (we say) embraces the fuller figure, the real woman. Rembrandt loves a heavy, stretched, experienced skin. Ah, how far it all is from the grim, size zero, perfecting, flesh-denying madness of our own fashion world. But if you're ever tempted to think that way, remember Lucas Cranach. You won't find a stranger or more artificial body-ideal on any modern catwalk or glossy cover.

With snake-like torso and frog-like limbs, his Venus appears against darkness. She stands on a kind of display podium, on a shallow rounded foreground of earth, like the rim of the Little Prince's little planet. She poses with outright provocation. She conceals her privates with the most plainly transparent and indicative piece of veil. She plays this light, soft strip of material floatingly across her thighs. She arouses sight and touch.

But the most striking aspect of Cranach's sexual imagination is the body he makes. She is a creature of the flat picture. She is an impossible model. Cranach uses the same devices used by that fashion magazine team when it silhouetted the woman's body and then made additions and subtractions. But here the operation has a difference. It's done in reverse.

Venus is not clothed in black. She is naked and fair skinned and seen against black. Her nude body is, in a sense, fully in sight. Yet the forms of her flesh are sufficiently smoothed over that she becomes, almost, a "white" silhouette. She has a body whose internal modulations are suppressed, and her anatomy is to be deduced principally from what her outer edges convey.

Cranach makes free with those edges. He pares out his goddess's form into a taut, slinky profile. But try to think how such a figure would be sculpted, or if it could be. It can't be imagined into solidity. This is a body that can only exist on the flat.

Yet the effect is stranger still. "White" silhouette can't be contrived as black silhouette can. Venus's internal flesh cannot be entirely vanished away, without it looking bizarre. Her breasts and tummy and muscles have a faintly rounded presence. On the other hand, they cannot be made consistent with the weird and essentially flat body that's implied by her outer edges. A contradiction arises between her contour and her flesh.

It gives a queasy feeling. The figure is as flat and sharp as a piece of snipped out paper. The body within this shape is as formless as beaten egg. Like soft cake-mix in a tin cookie-cutter, this flesh can offer no resistance to the hard, sinuous contour that Cranach binds it in.

But it's the object of erotic art to dream impossible dreams, to propose physical sensations you could never come across in reality. Cranach's Venus is a landmark of sexual fantasy. It must be someone's idea of fun.

About the artist

Lucas Cranach the Elder (1472-1552) was a staunch Protestant and a celebrated eroticist. He came from South Germany, and spent most of his career in Wittenberg, and never absorbed the ideals of Italian Renaissance. His painted world is one of high craftsmanship – hard-carved, densely patterned, with wine-gum colours gleaming in gem-like segments. His business embraced propaganda for both religious sides, Reformers and Catholics. He did portraits of Luther and grotesque peasants, altarpieces and comedy classical narratives, parades of serpentine nudes or elaborate costumes and hairdos.