Great works: A Democrat (or Ca ira!), James Gillray (1793)

British Museum, London

There is an artistic effect that might be called "breaking the surface". It involves a kind of lurch out towards the audience. At a certain point, the work suddenly becomes more real, more immediate, more present. It speaks to you with startling directness. It doesn't feel like art. It grabs you. What was writing becomes a word spoken straight at you. What was an image becomes something you can touch.

For example, there's a frightening fragmentary poem by John Keats, "This Living Hand". It is the speech of somebody who's threatening to haunt somebody else from beyond the grave. Here's the whole of it:

This living hand, now warm and capable
Of earnest grasping, would, if it were cold
And in the icy silence of the tomb,
So haunt thy days and chill thy dreaming nights
That thou wouldst wish thine own heart dry of blood
So in my veins red life might stream again,
And thou be conscience-calmed – see here it is –
I hold it towards you.

After six lines of gothic blood-curdling, the shock comes at the end, in the last phrases: "see here it is – / I hold it towards you." They break the surface. The words really seem to hold out a hand to you, to thrust it in your face. It's as if a character on stage, delivering a soliloquy, suddenly turned and looked you in the eye and addressed you by your name. You believe that he's there.

The shock is partly done with a style-shift, a change from a literary English to a much plainer and more direct English. Mainly it's in the way we relate to the speaker of these words. For most of the passage, he was just a voice, talking, a disembodied literary effect. But at the end he becomes a body, physically present: "see here it is – / I hold it towards you." You thought you were just listening. You hadn't realised – until this moment – that you and the speaker were visible and tangible to one another.

That's a poetic version. There are also pictorial versions. There are images that begin as a form of depiction and end up as something literal. They break through their surface and their pigment. Keats's hand reaches out of the passage and into our grasp. James Gillray's effects are even more material, more visceral. He offers a hand directly to our own hand. And his hand is steeped in blood.

The hand in question belongs to Charles James Fox. And from one point of view he was a distinguished Whig statesman, a hero of liberty. But not here. Here he is the opposite, a jeering and savagely partisan caricature, a monster of the French Revolution. Gillray calls him "A Democrat" – the worse name he can give to him, the leader of a mob, a murderer. A caption adds further ironies: "Reason and Philosophy".

This creature, on the other hand, is a rough, dangerous, absurd figure. Gillray shows Fox with an animal body. His skin and his bulk make him grotesque. He is swarthy and sluggish and his face is oafish. He stands there, with a jaunty one-foot gesture. His hairy legs are like a werewolf's. The caricature laughs at him, and he laughs back.

He bears the badges of the Revolution. He shows the behaviour and the costumes of The People. His bare-arsed appearance signifies his sans-culotte uniform (the expression is actually figurative; the crowd wore these short trousers). His shirt flies out and he farts into the wind. In a speech balloon, he cries out the citizen's blood-thirsty song: "Ça Ira!" "We will string up the aristocrats!.. We will win, we will win, we will win." And on his wig he pins his tricolour cockade – red, white and blue.

These colours are the Republican symbols of liberty, equality and fraternity. But there is also – ironic again – a visual theme. Fox's jacket is blue and his shirt is white. The blood on his knife and his arms is red. We understand this jolly spirit of massacre. This right hand is posed on one hip like a hornpipe. The left one is raised up like a salute, spattered with gore, and hailing the viewer.

Blood, blood, blood. Or as Keats put it: "see here it is – / I hold it towards you." This is where the picture becomes specifically violent. This is where "breaking the surface" occurs and touches our own hands. Fox's left hand is the crucial thing. His five fingers are spread wide. His palm is turned flat to the front of his gesture. His palm is also set face-on to the flat surface of the image itself.

Gillray has created a beautiful shock. The point is that, not only Fox's palm, his blood too, is laid flat to the image. His blood becomes literally the medium of this print. His stained surface is equated to the ink-marked page. Red blood is red ink. The fictional blood of this drawing is here as real as the tangible ink on the page.

His hand, our hand, and between them the paper, and the blood-cum-ink lying on it... We could physically run our fingers over this surface. Or coming at it the other way, Fox's murderous palm is pressed incriminatingly onto the page itself. And those two points of contact become one, in both pleasure and cruelty. It's clear that Gillray's caricature is more than morality or offence. He richly delights in his outrage and invention and horror and comedy. His genius breeds monsters.

About the artist

James Gillray (1757-1815) was the creator of the modern political cartoon, and much more. He lived above the London print shop that distributed his work. His subjects were social, party political and ideological: Pitt and Napoleon at table, with the world on a plate between them, carving it up; the Prince of Wales immobile with food; diabolical Jacobins in cannibalistic ecstasy; treacherous Paddies, honest doltish John Bull. His satire was generally anti-democratic. He had a taste for physical gross-out. His images were vicious, viscous – and visionary. He was an artist manqué who filled his caricatures with high art references, and could out-sublime all the painters of the Royal Academy. Critics, baffled, compared him to Michelangelo. In imagination he rivals his exact contemporary, William Blake. This particular caricature, and other Gillrays, can be seen in Rude Britannia: British Comic Art at Tate Britain until 5 September.