This World Cup has given the nation a chance to present an image of youth and optimism, writes Tom Humphries, but can it last?

For Germany the party is winding down. A third-place play-off for the national side in Jürgen Klinsmann's home town of Stuttgart tomorrow, a final in Berlin the following day and then the clean-up and the hangover and the inevitable question. What next?

It has been a curious month in the history of Germany. There is a strand of thought which suggests that for the first time since the last war the Germans have learned to love Germany and to be proud of Germany.

For the outsider it is an appealing notion. The sight of German flags fluttering everywhere and painted on the cheeks of seemingly everyone under the age of 20 is a phenomenon which few people harbouring notions of the stereotypically grim German expected to see. It is easy and tempting to read too much into it all.

Older Germans have a different slant.

Sure, the current generation, those with their faces painted and their flags waving, have been raised with a consciousness of the Holocaust and the war, but they are the first generation not to have been raised with the reflex of shame about any sort of German nationalism. That's one factor, they say.

The other is that this guilt-free generation just like to party. The new German colours, Bild newspaper has observed, are black, red and horny.

"For the past month Germans have been like the Japanese," says a German journalist who has lived outside the country for some years, "they put on the jerseys of other teams and they go out and party. I don't think it is much deeper than that."

It is true that, like the Japanese at the last World Cup, the Germans have been turning up at games en masse having picked a side to support. When Spain played France it seemed as if half the stadium was Spanish. In fact, thousands of Germans had come along in Spanish jerseys for an evening's entertainment.

So perhaps the last month has been nothing more than skin deep. Klinsmann has till the middle of August to decide whether to continue as team manager. Many expect him to return to his quiet, secluded life in California, possibly to become the next manager of the US national team.

So if the clean-up is done and Klinsmann is gone, will the World Cup have made any long-term radical difference to Germany? Klinsmann has been more than just a manager to the national team, he has been an emblem of optimism and youth and positivity. He is the manager who beat city hall.

By the time Ireland come to Stuttgart in September, how much of his legacy will be intact? Great fuss has been made of the superficial these past few weeks. The black, red and gold flag-fest has been hailed as a boost to Germany's integration of its immigrant citizens. It's true many Turks and Arabs flew the German flag at their shops or from their cars, but in an atmosphere of such fevered excitement it made sense to do so. A lot more is needed if the past month is to have a broad and long-term impact.

Take Nuri Sahin. In Germany they have him pegged as the next Roy Keane. Born in Ludenscheid, he has always been a prodigy. Last August he became the youngest player to have played in the Bundesliga when he lined out for Borrussia Dortmund against Wolfsburg aged 16 years and 335 days. A few weeks later he became the youngest player to score in the Bundesliga.

When Germany played Turkey last year in a friendly, Sahin was introduced for his international debut with five minutes to go. He scored the winning goal. For Turkey.

"I learned my football in Germany," he says, "but as a Turk I have never thought of playing for Germany."

Sahin is the pick of the young players in the Bundesliga and Dortmund have gotten used to rebuffing Arsene Wenger's inquiries about the kid. Sahin says he wants to grow old with Dortmund, but though born and reared in Germany he considers himself a Turk.

He is not alone. From the Bundesliga, Yildaray Basturk, Umit Davala, Ilhan Mansiz, Hamit and Halil Altintop are of similar background to Sahin and have opted to play for Turkey.

Their reasoning in understandable. Last season, at a lower league game between Hamburg St Pauli and Chemnitz, the fans of the visiting Chemnitz side ran amok after the game, attacking Turkish-owned shops, chanting "Sieg Heil" and "we're going to build a subway from St Pauli to Auschwitz".

In another incident, Adebowale Ogungbure, a Nigerian midfielder with lower league Sachsen Leipzig, was coming off the field after a game when he was racially abused and spat at. By the time he got to the tunnel fans were hanging down making monkey noises at him. Incensed, he put his finger to his upper lip making a Hitler moustache and gave the fans a Nazi salute. Such a gesture is unconstitutional in Germany and Ogungbure was arrested, although, sensibly, charges were dropped.

And back in the spring Germany was shocked again when an Ethiopian, who had been living here since 1987, was attacked while waiting for a tram in Potsdam outside Berlin. The man was speaking on his mobile phone, leaving a message for his wife when the attack occurred, and Germans were shocked to hear attackers shout "we'll finish you, you nigger".

In the former east of the country, where prosperity hasn't touched everybody and where the resentment of foreigners is high, the far right parties are at work.

It has been a great and wondrous month for Germany and for Germans, but if it is to mean anything the World Cup must be seen as a starting point rather than a culmination.