Last weekend, Arsenal played their final league match at Highbury, an occasion that was at once a celebration and a long goodbye. No one seemed to be living more intensely through those last moments at the venerable stadium in north London than Arsène Wenger. Knowing that his team had to win the game to have any chance of finishing fourth and thus securing a place in the super-lucrative Uefa Champions League, he was unusually hyperactive, especially early on when Arsenal were losing, continuously on his feet and gesturing in manic agitation.

After the match, with Arsenal's place in the Champions League secure, Wenger joined his players on a slow lap of honour. I have never before seen him so animated as he signed autographs and touched hands with some of those in the stands chanting his name.

And what a name. When Wenger arrived at Arsenal in the autumn of 1996 as one of the first foreign managers in the English game, he was, inevitably, received with suspicion and bewilderment. Who was this Frenchman with the German name, from the contested eastern borderlands of Alsace, and what was he doing at Arsenal of all places?

Wenger was tall, alarmingly thin and wore wire-framed spectacles. He did not look like a football manager so much as an academic or perhaps an EU bureaucrat. He had come from Japan, where he had been coaching Nagoya Grampus Eight, who are not exactly among the élite sides of world football, as Manchester United's Alex Ferguson, who would soon become his bitter rival, remarked contemptuously at the time.

Wenger spoke good English, with a slightly comical accent, had a degree in economics from Strasbourg University, and, with his interest in sports science, nutrition and physiotherapy, had progressive ideas on how a modern football club should be run and how its players should eat, train and rest. The Arsenal players, then mostly English, and with some hardened boozers among them, called him 'the Professor'. What else?

Perhaps the defining moment of Wenger's time at Arsenal occurred soon after his arrival. Scurrilous rumours were circulating about him and one afternoon journalists began to gather outside Highbury, as if poised for the kill. Ignoring advice from inside the club, Wenger decided to confront them. He went out on to the steps outside Highbury's art deco entrance and challenged the journalists to publish what they claimed to know: 'If you print anything, I will attack.' By which he meant he would sue. Nothing was published. The rumours stopped. Wenger was free to get on with his job.

Those close to him say that he has never forgotten or forgiven how he was treated in those early days in England and he remains one of the most private men in football, reserved, distant, fastidious. Unlike Sven-Göran Eriksson, he is never seen out at smart restaurants or clubs. Wenger once joked that all he knew of London was the journey between the home in Totteridge he shares with his long-time partner, Annie Brosterhous, a former schoolteacher and basketball player, and the Arsenal training ground at London Colney.

'He lives quietly,' says French writer Philippe Auclair, who has followed his career. 'Once the football is over, he likes to go home. Sometimes, if he needs to think, he will go for a long drive and listen to classical music. Football is his obsession, yes, but he has a hinterland. The abstemious Arsène is a complete myth. And let me tell you this: Wenger never lies. He has great moral integrity.'

The essential unknowability of Wenger - the mystery and fascination of him - is heightened by his refusal to play the media game or embrace celebrity. While he is always available for press conferences, he never gives long interviews to British journalists or speaks candidly about personal matters or issues outside football. This is a shame because it means we shall never know him as he really is. Close friends comment on his sense of humour and mischief and his fondness for food and fine wine, especially the reds of Bordeaux.

Nor is Wenger popular among his fellow managers, who complain about his aloofness. Alex Ferguson once spoke with irritation of how Wenger would never join him for a post-match drink, a cherished tradition at Old Trafford.

Yet he is adored by his players, to whom he is unstintingly loyal, never criticising them in public. 'He is one of the most knowledgeable people in football I've ever met,' former Arsenal defender Lee Dixon told me. 'He's got such faith in his players and his faith and confidence inspire you to try even harder, to succeed for yourself but also for him.'

When Wenger arrived at Highbury, Arsenal were struggling, having not been in contention for the league title since they were champions in 1991. The celebrated defence, led by Tony Adams, who would soon announce that he was an alcoholic, was ageing, and a previous manager, George Graham, had been sacked for financial impropriety. Arsenal were respected, but never admired; their style of play was dour and predictable.

Wenger rapidly transformed the fortunes of the club, bringing in young, unknown players from overseas, especially from France, such as Patrick Vieira, and from Francophone Africa, and encouraging his team to play with a new-found pace and élan. Soon, one of England's most traditional and conservative footballing institutions would be transformed into a model of racial and multicultural integration. They were the first truly globalised team.

Honours followed quickly, with Arsenal winning the Premiership and FA Cup double in 1998, the beginning of a long sequence of success that, on Wednesday night, when Arsenal take on Barcelona in the Champions League final, may culminate with the club winning the greatest honour of them all for the first time.

It has been a long and curious journey for Wenger to his present serenity and pre-eminence. He was born in Strasbourg in October 1949. His father, who had been conscripted into the German army, owned a modest restaurant. Wenger, like many of the best foreign coaches who have worked in England in recent times - Gérard Houllier, Mourinho, Eriksson - was never much of a player himself, scarcely rising beyond the level of semi-professional in the French league. His first coaching job was at Strasbourg, from where he moved to Cannes, then AS Nancy and, in 1987, to wealthy Monaco, where he lived alone in a small flat and studied videos of matches and players with unusual dedication.

'In those days, he was very beautiful,' says Auclair. 'There are pictures of him in which he looks perfect for the role of Tadzio, the beautiful boy in Death in Venice. He was also very intense and jumpy on the touchline, nothing like the composed figure of today.'

Wenger won the French title in his first season and, always at ease with black players, brought Liberian George Weah over from Cameroon in a remarkable coup. Weah went on to become the greatest of all African players.

Wenger's seven years at Monaco ended in disappointment, in 1994, with the sack and the realisation that his main rivals, Marseille, under the ownership of Bernard Tapie, had been winning matches through bribes. 'For Wenger, his life in football has been a journey from innocence into disillusionment,' says Auclair. 'He first lost his innocence when he discovered that Marseille were buying victories and yet he still believes in rules, in morals, in certain codes of behaviour - and in his players.'

Last weekend at Highbury, as he stood being interviewed on a podium in the centre of the pitch, Wenger reflected on the 'special qualities' he had found at Arsenal and on how his teams had always played with spirit, togetherness and 'yes, even sometimes art'.

It is easy to buy success in football. Surely it's far better, though, to achieve success without paying grotesquely inflated transfer fees for readymade superstars; to achieve success, as Wenger has, through the discovery and nurturing of talented young individuals, from all over the world, and making of them, through the collective expression of the team, something remarkable and lasting?

Next season, Arsenal will be playing before 60,000 spectators at every home game. They are poised to become one of the true superpowers of world football. Wenger will be there to lead them out at the new stadium.

But one can't help thinking that soon, and especially if Arsenal win on Wednesday, that he may feel his work in London is complete. Already, he has said that reaching the final in Paris is 'the culmination of the work of nine-and-a-half years at the club'.

One hopes that he will stay at Arsenal for a little longer because, in spite of all his inscrutability and reserve, Arsène Wenger has effected a glorious revolution here in England, showing us not only how the game can and should be played - 'yes, even sometimes art' - but how young men of different races, religions and nationalities can work together harmoniously to create a moral example and vision of the cosmopolitan good life.

The Wenger Lowdown

Born: On 22 October 1949 in Strasbourg. Lives in the London suburbs with long-term partner, Annie Brosterhous, a former schoolteacher, and their young daughter, Leah.

Best of times: Almost all at Arsenal. His teams have won the fabled double of the league title and FA Cup twice, in 1998 and 2002. Last week's victory against Wigan, which ensured Champions League football next year. Perhaps the best is yet to come: his greatest triumph would be to win the Champions League final against Barcelona this coming Wednesday in Paris.

Worst of times: Sacked as manager of Monaco in 1994; discovering that his main rivals, Marseille, had been 'buying' victories.

What he says: 'Jam rolypoly and custard? It's silly to work hard the whole week and then spoil it by not preparing properly before the game. As a coach, you can influence the diet of your players. I can teach the players what they do wrong without knowing it is wrong.'

What they say: 'He just lets you express yourself and be who you want to be. That's very special and you don't have that with everyone. Sometimes, you have a boss who wants to run the show. Arsène isn't like that and besides being a great boss, he is also a great human being.' Arsenal player, Thierry Henry.