Boxing clever in white to lure modern crowd

In Henri Rousseau's The Football Players (1908), men play rugby between trees in the Luxembourg Gardens. All of them have a dream-like quality that is the secret of their power.

Art in all its manifestations is enormously popular in London. People throng the National Gallery to look at the art of previous centuries, but the real celebration is of the modern and the contemporary.

The phenomenally successful Tate Modern is even more crowded with people, especially young people, admiring work that even 20 years ago would have been dismissed as odd manifestations of an intolerable "modern art".

Across the Millennium Bridge to the Tate Modern come masses of couples, a high percentage pushing push-chairs or with children in tow, and the first place they visit is the vast Turbine Hall to see the latest response to the challenge of making a work to fit the immense space.

The artist taking on the vastness right now is Rachael Whiteread, whose reputation is based on such feats as casting the complete inside of a house. Her installation in the Turbine Hall is made up of thousands of white boxes stacked in a variety of ways with pathways between them. The whole installation is not visible from any one site, not even from the balcony above. The polystyrene blocks are icy white, in several sizes, moulded on the inside of cardboard boxes.

The artist's original impulse came from a cardboard box in which her toys were kept when she was a child, but there is no sense of this connotation to the viewer. What has been created is a towering abstract version of a town where an extraordinary variety of structures exist. Some have the tumbled blockiness of ruins, others the precise geometry of apartment blocks.

The structure's huge black steel girders contrast with these chilly, doorless and windowless structures.

The principal stimulation as you wander in this maze is to take part in the decisions involved, because each structure has its own logic.

You can see that once you start in a certain way, the subsequent levels have to be congruous unless a sudden decision is made to depart from logic by tilted or diagonal blocks.

There is a certain cold brilliance about the installation and, despite its size, it looks fragile. Attendants warn those pushchairs away from the base of the stacks as the crowds weave their way through it.

It's even more packed on the third floor, which is given over to a large exhibition of the most famous self-taught artist of all time - Henri Rousseau, who was born in 1844.

At the beginning of the 20th century his naive work was much admired by artists and poets in Paris. Picasso collected examples of his work.

Rousseau began painting in middle age after working for years as a customs officer in the tollbooths of Paris.

The exhibition is called Jungles in Paris because the most spectacular paintings show intense leafy jungles populated with tigers and monkeys, snakes and a snake-charmer.

Rousseau claimed to have seen such jungles, but in truth most of his observation of tropical growth was at the Jardin des Plantes in Paris.

Not all the works are of jungles - many of the most appealing are scenes from the Paris he knew. There are some polemic political paintings and one crazy painting of men ostensibly playing rugby between trees in the Luxembourg Gardens. All have a dream-like quality that is the secret of their power.

The first painting is the popular Tiger in a Tropical Storm on loan from the National Gallery. In a forest of enlarged plants and grasses which make dense patterns, an oddly comic tiger, all teeth and eyes, stalks its prey. All the rhythms of this painting sweep to the right as the wind rips through the forest. There is white lightning in the sky and thin, transparent paint streaks down as rain.

There is red and yellow in this painting, but above all Rousseau's work is notable for his use of green. Not only are his patterned jungles green but the paintings of the parks around Paris gain effectiveness by the variety of shades of green.

The painting of his workplace, The Customs House, is notable for the green of trees and hills, but there are also two factory chimneys prominent in the work, and factory chimneys and everyday dress had their part.

What is enchanting about Rousseau's work is the oddity, atmosphere and clarity which makes the images stick in the mind. As well as the jungle pieces he found poetry in the everyday reality of his own life.

This is why The Football Players is so memorable. In it there is a leafy avenue of trees in the public gardens. There are only four players but they are dressed in striped football gear.

They have bristling moustaches and strike unlikely poses. Their quirky attitudes are similar to the monkeys in Rousseau's jungles. It is those jungles that most attract the viewers. Surely this is because they foreshadow some main features of modern art, and it is the art of the moment that captures these crowds.