By Stephen Mulvey
BBC News website in Brussels
As the leaders climbed out of their shiny limos, one by one, smiling from ear to ear, one could not help wondering: crisis, what crisis?
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There were handshakes, backslaps, hugs, even kisses - for the Austrian Foreign Minister, Ursula Plasnik - as the prime minister of Luxembourg welcomed the visitors to the summit.
Only the UK's Tony Blair looked strained, as he grasped Jean-Claude Juncker's hand and showed his teeth to the cameras.
French President Jacques Chirac, who has been known to go on the offensive before even getting through the door, looked cheery - and this time made no comment to reporters.
But everyone knows the gloves could come off at any moment.
Probably they will before the end of the two-day summit, once the discussion turns to the UK rebate, and the Common Agricultural Policy (CAP).
However, to judge from the scraps of information leaking from the chamber, the first session began in a mood that was neither cheerful or belligerent, but mournful.
"It is with a certain gravity that I take the floor this evening, in a context that is difficult for France, and whose consequences for the whole Union I can well understand," said a chastened Mr Chirac, referring to the French vote against the constitution.
He called for a "spirit of togetherness and unity" and a "will to respond to the message of the people".
'Bring it on'
By all accounts, many other leaders struck a similar tone, using words like "pause", "period of reflection" or "time out", which they said should be used for a "debate" or "dialogue" with citizens.
But Mr Juncker made clear in a press conference at the end of the day that the treaty would not be renegotiated, whatever the result of this dialogue.
"I really believe neither the French nor the Dutch rejected the constitutional treaty," he said.
He argued that they voted against the way Europe is now, not the Europe proposed by the constitution.
The "No" votes were inevitably the key focus of discussion.
"No-one can take consolation from the French or Dutch 'No's'," said Tony Blair, in his speech to EU leaders.
But from the UK's position, there is potentially a positive side.
The French "Non" weakens France's standing in Europe.
It strengthens the UK's arm in its battle with France over the UK rebate and the CAP, and improves London's chances of pressing ahead with an economic reform agenda during its EU presidency, in the second half of the year.
UK officials clearly relish the struggle.
"Bring it on!" said one, in conversation with a BBC colleague.