Stubbs, George: Dungannon, with a Sheep (1793)

Symmetry is a game of two halves, but humans usually experience it in a particular way. It's an affair of one side and another side " rather than, say, above and below. An arrangement of ornaments on a mantelpiece is a typical case. Left is reflected by right: the symmetry is lateral; the axis of the symmetry is vertical. Symmetry may, of course, occur at any angle. Its axis can be horizontal, or diagonal. But for humans, symmetry tends to mean of two matching, mirroring sides.

This comes down to certain general facts of nature. The earth is underneath the sky. Gravity descends. Humans stand on the earth. Things line up along the ground. When symmetry occurs in the natural world, it's more likely to be a hill mirroring a hill, than a hill mirroring a cloud. And human beings themselves are symmetrical around a vertical axis, and have filled their world with things that are symmetrical in a similar way " beds, windows, houses, temples, streets, countless other artefacts.

When a man is sick of symmetry " presumably this is behind Buñuel's line " he isn't just rejecting a conventional design preference. He's rejecting a fundamental dimension of human life.

European painting has a fluctuating relationship with lateral symmetry. It's an obvious way to organise a picture: something in the middle, with two balancing wings. But at some points in history it comes to seem boring, crude, simple-minded, formulaic, and more complicated kinds of balance are sought. Then at other times it seems pure, authentic, powerfully primitive, ritualistic, and has a comeback. But in any picture, symmetry is a latent possibility, a pull. Any picture can be looked at in terms of how far it succumbs to or resists this pull.

George Stubbs' animal paintings often toy with symmetry. He is a great one for lining things up along the ground, and across the picture. With racehorses, with hounds, he sets them out in rows that have both the composure of a classical frieze and the stiffness of a livestock inventory. It's a way of displaying the fine contours of these well-bred creatures, and of suggesting how well trained they are too " composition as dressage. It has a sense of both the dignity and the comedy of animals. It can be hard to catch Stubbs' tone, to gauge how far he means a creature to be immensely noble or slightly absurd or something of both.

Dungannon, The Property of Colonel O'Kelly, Painted in a Paddock with a Sheep, was one of a series of horse portraits that the Turf Review project specially commissioned to commemorate the great names of late 18th-century British racing. But there's obviously some incongruity joke here too " a collision of high and low, organising the whole scene.

A serene formality prevails. There is a rigidly frieze-like parade. The two animals are set in statuesque poses. They are stood, toeing the same perfectly straight line. They are shown in the cleanest profiles. Their shapes are made to match, and they face each other directly. The whole arrangement announces a symmetrical equilibrium, except...

Except that, obviously, just on that point, there's a crucial disparity. The high and beautiful thoroughbred is 'balanced' by a small opposing sheep. The symmetry stakes are raised to the max, and then collapse. The layout says: two creatures of matching dignity, and it's as if they had an 'equals' sign between them. But the layout is spectacularly let down by the subject. The 'equals' sign bumps into evident inequalities of these beasts.

The result is, each animal makes the other look funny. The low sheep makes the horse look funny, by mirroring and mocking its elegant stance. The horse makes the sheep look funny, by offering a model of dignity that it can't possibly rise to.

The effect isn't just a matter of failed symmetry. If you took the horse away, and had a picture of this sheep alone, there'd still be some comedy. Its highly formal pose is enough by itself to set up an incongruity. A sheep can't really handle the stately pose Stubbs gives it. It is an excessively dignified, a mock-dignified way to portray a sheep.

On the other hand, if you took the sheep away, and had the horse standing alone, it wouldn't look funny at all. The nobility of the thoroughbred is fully equal to this classical formality.

But it would be wrong to lose the symmetry effect, either way. You need it, not just for the sake of a funny incongruity, but for the sympathetic animal truth within this incongruity. The picture is saying something more interesting than that a horse is grander than a sheep. That would be a silly joke, just by itself. It's saying that, despite appearances, there really is an equality, a shared dignity, a true symmetry, between these two particular creatures.

What is the sheep doing here, anyway? A contemporary of Stubbs noted: 'The great attachment of this horse to a sheep, which by some accident got into his paddock, is very singular.'

In fact, it's not all that singular. These dependency relationships happen. Nervous thoroughbreds do sometimes have a companion sheep or goat or donkey, some less highly-strung animal, living along side them; and it keeps them calm, it balances them.

THE ARTIST

George Stubbs (1724-1806) is the best English painter. Not Gainsborough, not Reynolds, not Constable, not Turner. Stubbs the horse-painter wins by several lengths.

But this is an argument that needs more space. Stubbs began his career with a full-scale visual analysis of the horse's anatomy. He went on to raise the semi-naïve, vernacular practice of animal painting to extraordinary heights. He makes the horse a universal metaphor: highly bred, trained and socialised, or romantically wild, or a model of a utopian society. He is a master of design " of shape, rhythm, interval, repetition-with- variation. He is a great colourist.