A few years ago, I saw a Mondrian show in Pittsburgh. A career in one room, it began with a farmyard scene in the Dutch genre style Mondrian favoured in 1900 and ended, 20 years later, with a colour-rectangle Composition. In between, things changed incrementally – Mondrian finding Cézanne, then Cubism; his eye becoming more linear, grid-like; his abstraction less a rejection of nature than a refining of it. The show's history may have been on the tidy side, but it was compelling for all that.
In 1964, Roy Lichtenstein painted a Mondrian, Non-Objective I. I say "a Mondrian" because that is what it is – not a specific picture but a generic one, a Mondrian-a-like. It is not one of Lichtenstein's better-known works, although it is one of his more revealing. Halfway through Tate Modern's new retrospective, in a room labelled Art About Art, Non-Objective I considers how Mondrian made it from farmyards to rectangles.
All painting is about inventing a system, a code of marks or forms to say what you want to say. Ingres used a fine brush, close-worked; Seurat, short, stabbed points of coalescing colour; Mondrian, rectangles of red, yellow and blue. His system seems to go about as far systems can, although any brushload of paint applied to a canvas is exactly as abstract as any other, whether the end result is a colour grid or A Sunday Afternoon on the Grande Jatte. Art is, and always has been, about lying.
In Non-Objective I, Lichtenstein tips us off to this. Most of the image is straightforward Mondrian, except for the areas we read as grey. These are rendered not in solid paint but in Ben-Day dots, those printers' ink blobs Lichtenstein made his own. It turns out Mondrian hadn't taken abstraction as far as it could go, because Lichtenstein takes it further: he abstracts the Dutchman's rectangles into discs of colour. Except that, confusingly, Non-Objective I isn't abstract. It is the slavishly representational re-creation of a work by Piet Mondrian.
Confused? That is the point. In the room before, a picture, Tire, shows what we Brits call a tyre. But, of course, it doesn't. Lichtenstein has painted a system of black zigzag lines which we read as a tread, areas of black and white we agree is a hubcap. As with Warhol's starlets and soup tins, tyres are not the stuff of High Art: we are in the land of Pop. And yet Lichtenstein's work has a moral intent that is anything but popular.
Scholars of art history spend years dissecting the brushwork of Ingres, but the man in the street – the man at whom Ben-Day dots are aimed – takes it as read that a given arrangement of spots and zigzags is a tyre or a duck or a mouse. Objects of mass production need mass deception and collusion. Only when the deceit is shown out of context – on a gallery wall rather than in an auto magazine – do we see the trick.
The image of Roy Lichtenstein as a lyricist of Middle America – a poet of comic books, car parts, True Romance – could hardly be more wrong. There had been no single Whaam! moment in Mondrian's career, but there was in Lichtenstein's. In Ohio in the 1940s, he was influenced, like pretty well everybody, by Picasso; back in New York in the Fifties, he turned, like many artists, to Abstract Expressionism. But when, in 1961, his young son challenged him to paint a page from a comic, something in Lichtenstein clicked.
Pop was in the air – Richard Hamilton had kicked it off in Britain, Warhol was painting images from Nancy comics nearby. Lichtenstein's Look Mickey has a different feel from these, though, a paternal tenderness. Just as Mickey can see the truth about Donald's catch – can titter at the double entendre of what the guileless duck is saying – so Lichtenstein understands his own role as an artist. Jean-Jacques Rousseau thought painting wicked because it tricked the eye. Lichtenstein feels rather the same way.
Above all, he is a history painter, a man of his time. The Ben-Day dot was merely the newest, the most dangerous system of visual deception, worse than Monet's brush-marks only because more efficient – Lichtenstein points that out in his re-making of Monet's Rouen Cathedral series. But the innocent printer's dot is not just an abstract form. It is also the tool of a capitalist structure, a mass means of gulling the masses.
The Tate's own Whaam! may be lifted from a comic, but it was painted in 1963, as America became embroiled in Vietnam. It is a history painting, the portrait of a time when war had been made the stuff of bread and circuses, a plaything for children including Lichtenstein's own. That realisation, maybe, is what makes him a great painter. His art is often funny, intentionally glib; but it is, at heart, tinged with despair.
To 27 May (020-7887 8888)
Glam! is waiting to take you back to the Seventies with art, music, photography and plenty of spangly ephemera. Style, sexuality and nostalgia combine in this wide-ranging show at Tate Liverpool (till 12 May). There are more exclamation marks at photographer Juergen Teller’s show Woo!, at the ICA in London. The work showcased features wellknown fashion faces, actors and rock stars, from Lily Cole to Kurt Cobain (till 17 Mar).