The left leg of La Belle Hollandaise is one of the great limbs in art. It's a heavy thing, laid across a bed, looking rather like the leg of a chicken, with a vast drumstick of thigh and buttock, but taking a stout but more shapely turn below the knee, and ending (now entirely human) in the elegant point of a toe. You can vividly grasp its outline and mass, feel its tautness and muscular tension. You can grasp its "moral", too; that though not conventionally beautiful, it is magnificent, grandly feminine. This leg is something definite to hold on to in a body of work that proves in every other way bafflingly elusive.
In the early years of the 20th century, Walter Sickert made a sequence of paintings known as the Camden Town Nudes. They weren't painted all in one go, or shown all together in a single exhibition. But about 20 of them can now be seen at the Courtauld Gallery, in a show that opens on Thursday, and it's clear that they have the marks of a series.
A naked woman lies on a bed. It's a basic, iron-frame bed, set in a room in a cheap north London lodging-house. A few other props are usually visible - chest of drawers, washstand, mirror, curtain.
The rooms are dim or dark, pierced by daylight. Highlights gleam off metal and flesh, but the colours are murky - greys, browns, mauves. The paint is put on in a broken, blodgy way. Everything feels somehow grimy, ingrained with dirt. There is sometimes a second figure present, a clothed man, standing or sitting. The scenes are tightly framed. An air of claustrophobia, menace, violence, is common. Some of the titles have the word "murder" in them.
Sickert (1860-1942) has an uncertain, never quite canonical standing. He was one of the artists who introduced "modern art" - that is, late 19th-century Parisian art - into British culture. He had lived in Paris, and knew Degas and Bonnard and all the movements - Realism, Impressionism, Post-Impressionism. But as a very young man, before becoming an art student, he had also been on the stage, acting in Henry Irving's company, and his theatrical impulses are strong, too.
He painted pictures of the London music halls, and end-of-the-pier shows, and low-rent domestic interiors. Long before Pop Art, he based pictures on photographs in newspapers. He was interested in crime. He thought he knew the identity of Jack the Ripper. He has sometimes (improbably) been identified as the Whitechapel murderer himself. But even as an artist he's been a bit too hard to pin down for his own good.
Let's stick to the facts, for a while. These Camden Town Nudes are, at the very least, nudes. You might say that, in the end, that's all they are. They have the unmotivated nakedness, the general lack of motivation, of the studio nude. No shed clothes are in evidence. The women are just lying around on beds, not doing anything, except being painted.
True, they're defiantly unidealised nudes. Sickert abominated the smooth, firm, geometrical, depilated figure taught in art academies. His models have heavy, floppy bodies. They lie in casual, exhausted or explicit poses, legs splayed, pubic hair marked. "The plastic arts are gross arts, dealing joyously with gross material facts," Sickert said, and he could turn a phrase. But "joyous" isn't a word you'd readily associate with any of his painting.
The realism of these nudes is stressed by setting them in real, downbeat places. Sickert rented rooms around Camden Town and Mornington Crescent, and set up his studio there. That introduces a tension. The nudes are no longer simply nudes. The setting adds a dimension of lifestyle and life-story, which then makes you wonder: why exactly are these women lying around naked on the bed in the middle of the day? And the obvious answer, that they're prostitutes, is certainly available - except that the pictures don't do quite enough to substantiate it.
The paintings keep raising doubts - about what they're of, or what their attitude is. Is the series a frank documentary look at the hard facts? A bourgeois-baiting shocker? A bohemian romanticising of low life? Or is it something rather more dramatic and melodramatic?
The pictures don't say much overtly, but they're full of suggestions, and the suggestions are mainly dark. They tap into the 19th-century mythology of London, created by Dickens and Gustave Dore, with its soot and miasmic fogs, its huddled slums and demonic underclass; likewise into a fin-de-siècle mythology of the fatal woman, lolling, unclean.
The uncertainties are lodged in the very way Sickert paints. It's clear that he has an ideal of free and dashing brushwork, derived from Manet - a painting that will do a swift but effective shorthand for reality, while making elegant and spontaneous-looking patterns on the canvas. He relishes the way the brush can flick in streaks of raking light, pile up a bedspread with rough dabs, fluently sketch the long outline of an arm. His touch can be very tender.
But he's also aware that, done very freely and economically, this virtuoso procedure will generate weird and unreadable obscurities that completely override the "gross material facts". There are pictures like Nuit d'Ete, where the body's flesh melds and mulches into the bedclothes, where shading and void and dirtiness become indistinguishable. There are pictures like La Belle Hollandaise, where the model's face has been wiped right off her.
At a certain point, this begins to look like violence, as if the painter was brutalising the model, messing her up, doing her over, even as he paints her - or doing her in. You can wonder: these women, some of them, are they actually meant to be dead?
"I knew a man once did a girl in/ Any man might do a girl in/ Any man has to, needs to, wants to/ Once in a lifetime, do a girl in." That's TS Eliot, in a cartoony verse-drama from the 1930s. Sex-murder is a strangely prominent theme in early 20th-century art. You find it in Frank Wedekind's Lulu plays, and GW Pabst's Lulu film and Alban Berg's Lulu opera. You find it in images by George Grosz and Otto Dix. The crucial inspiration is Jack the Ripper, though since men are always killing women in domestic-erotic situations, there is never a shortage of models.
Sickert was interested in the Ripper, but he had a more immediate crime in mind. In 1907, in the middle of this series of nudes, a prostitute was murdered in Camden; it became a famous case. After that, Sickert gave some of the pictures titles like The Camden Town Murder, L'Affaire de Camden Town, The Camden Town Murder Series No 1 and No 2.
It is always pictures with a clothed man present that get these titles. But the point to notice is that the titles can vary. On other occasions, Sickert exhibited the same paintings with different names, carrying quite different implications - the social realist What Shall We Do for the Rent?, the lyrical or perhaps ironic-lyrical Summer Afternoon. And the pictures can take these alternative titles. There is nothing to identify them unequivocally as crime scenes. The encounter between naked woman and clothed man can be read as despairing or idyllic or murderous. Sickert is playing with the inherent dumbness of pictures and his own painterly obscurities. Only L'Affaire de Camden Town kept that title alone. The man stands "dangerously" over the woman. The woman "flinches". Well, maybe. But then again, maybe not.
Now, one shouldn't expect a work of art to be single-minded. Any half-decent work is likely to have a lot of things going on in it, and what's more, a lot of simply disparate things that can't be resolved into an overall agenda. But still, Sickert's Camden Town Nudes really are all over the place. They're abruptly torn between incompatible priorities - between nude study, documentary realism, pure painting, subtle story-telling, horror thrills, and doing some paintbrush sex and violence of their own. This isn't complexity. It's a big mix-up.
You can see Sickert as a very detached artist, an operator, who treats painting as a repertoire of possibilities that can be mobilised at whim, because none of it really means anything to him. Or you can see him as an artist who's not in control of himself, who just puts whatever excites him into the pot. Nowadays, of course, we like our art not to make sense. Sickert's time may at last have come.
Walter Sickert: Camden Town Nudes, Courtauld Gallery, London WC2 (020-7848 2526), 25 October to 20 JanuaryReuse content