Boucher and Chardin at the Wallace Collection

    Art has a handy way of dividing its practitioners into contrasting pairs so that the differences between them are easier to spot. Think how much simpler it is to characterise Gainsborough with Reynolds around to supply the opposites. Think Delacroix and Ingres; Picasso and Matisse; Caravaggio and Carracci. In all their cases, a pioneering set of aesthetic values appears to be encountering its alternatives. It is a process that achieved some sort of absurd rococo crescendo in the matching careers of Chardin and Boucher.

    Chalk and cheese have nothing on these two. Boucher would unquestionably feature near the summit of my personal top 10 of regrettable artists. Sly, sycophantic, corrupt and giggly, this bouncy peddler of soft porn was Madame de Pompadour’s favourite artist. Anyone wishing to understand why the French Revolution had to happen need only examine a handful of Bouchers. The stink of French 18th-century corruption wafts up from his art.

    Chardin, on the other hand, was a truly heroic presence. Surrounded by fops and fools, in a century that specialised in frippery, he managed somehow to create a body of work that impresses us with its solemnity and its weight. In his austere kitchen still lifes, Chardin could give a well-scrubbed copper saucepan the moral authority of a high-court judge. His entire career accuses his times of slightness.

    Having said all that, it probably needs admitting that nothing in art could ever be this clear cut. The possibility that Boucher was not all bad and that Chardin was not all good deserves a moment of consideration. And London’s prettiest museum, the Wallace Collection, is displaying uncharacteristic meatiness in building a fine exhibition around the telling contrast between Boucher’s Woman on a Daybed and Chardin’s Lady Taking Tea.

    Painted within a decade of each other, both of these pint-sized displays of French rococo thinking feature a woman, an interior and a teapot. Chardin’s woman, from 1735, is actually drinking her tea. Boucher’s, from 1743, has merely collected the fashionable porcelain that goes with it, and her unused teapot is on show behind her on an ornamental shelf. Were this the handiwork of someone else, it might be possible to accept that the picture has no sly or secret ambition to address the subject of sex. But this is Boucher. So we can be 100% certain that the woman on the daybed is displaying herself to collectors as pertly and enticingly as an expensive teapot in a Sotheby’s window.

    Tea turns out to have had an amusing social history, which the Wallace Collection skates over entertainingly at the start of its effort. Arriving originally from China, as part of the huge wave of oriental fashions that was to have such a powerful impact on 18th-century European tastes, tea seems to have been remarkably controversial at first. Half the medical fraternity applauded its medicinal properties, the other half warned of its grave dangers. According to Simon Paulli, author of the first authoritative medicinal guide to tea, published in 1635, this terrible foreign substance causes “effeminacy and impotence” in its drinkers. Others insisted that it led to “miscarriage and diminution of beauty” among women.

    The show also throws a couple of hilarious Hogarths into the mix to make clear the abominable fashionableness of tea. Hogarth, who mistrusted anything that originated beyond the English Channel, particularly if the French liked it, has enormous fun mocking an ageing English countess for drinking tea from a porcelain cup no bigger than a thimble, and for having a French cook, personified by a monkey in a beret, who holds up a menu featuring “duck’s tongues, rabbits’ ears and snails”.

    If Hogarth were around today, he would be working for The Daily Mail and calling himself Richard Littlejohn. It is vicious stuff.

    Hogarth’s incorrigible English need to mock and sneer leads to some decent belly laughs, but profundity is beyond his reach, so the arrival of Chardin in the display is doubly welcome. We can compare him not only with Boucher, but with Hogarth, too. In both their cases, it is as if two noisy schoolboys have had their iPods confiscated so the adults can speak.

    The display does not actually hang the Boucher next to the Chardin, as we might have expected, probably because a mouse can never look impressive next to an elephant. A direct comparison would have relegated the Boucher to the third division. It is a much smaller picture, anyway, not much bigger than the front page of The Sunday Times, whereas the Chardin is the size of a widescreen telly. Instead of hanging them side by side, the show gives us two mini-exhibitions built interestingly around them.

    Boucher’s Woman on a Daybed usually hangs in the delightful Frick Collection, in New York, surrounded by Louis XV fauteuils and Sèvres porcelain that perhaps exaggerate the softness of its mood. Stripped of rococo finery in this display, the picture acquires a harsher, more predatory presence. The woman, whose identity is unknown, lounges provocatively on her daybed and greets your arrival on the scene with a coquettish sideways smile. If spiders had faces, this, perhaps, is how they would feign indifference when an unsuspecting fly approaches the web.

    The disarray of the woman’s clothes, the carelessly open drawer by her daybed, even the big cascade of yellow silk at her feet, seem to speak of moral corruption. Underneath all the pretty rococo surfaces, Boucher appears to be hinting at powerful undercurrents of sexuality and violence. Even the porcelain teapot that is supposed to symbolise the owner’s fashionableness is so messily displayed that it, too, ends up drawing attention to her turpitude.

    I have to admit that Boucher impressed me more than I was expecting. His art has a knowing cunningness to it that gets turned on the viewer as well as the sitter. Yes, he is a peddler of soft porn, but the exact course of his intentions remains fascinatingly unchartable. Chardin is more solemn and less cunning. Lady Taking Tea belongs to the Hunterian, in Glasgow, where its particularly pale and austere brand of rococo appears to chime well with regional preferences. There is something so unFrench about Chardin: so modest and Protestant and plain.

    In this instance, we know that the woman is probably his wife, and that she is taking tea for medicinal reasons. Tea was supposed to help those who were “short of breath”; and, in real life, Chardin’s wife died of lung disease in the year the picture was painted. Knowing what we know about her, it is difficult to resist the idea that some recognition of her fate is fuelling her self-absorption. The pearly touches with which Chardin captures the wisps of steam rising from the cup that she stirs so absent-mindedly, and the thoughtful shadow that has fallen across her face, are masterfully done. Even if we knew nothing about her, we would certainly sense her melancholy.

    She, too, has an open drawer at her table, not because she is a useless housekeeper, like Boucher’s bedroom wench, but because she has neatly taken out the cutlery she needs for her sad little tea ceremony, and will neatly put it back again in a moment. The big, clunky teapot seems to be watching over her, as if it were Chardin himself. And something poignant is being said about the hope invested in a cup of tea.