At the kitchen table, in the middle of Ireland a fortnight ago, it hit me that Europe was in deep trouble. My mother had just announced she was thinking of voting "no".
If the doubts had reached a pro-European citizen such as her then this treaty, and perhaps the European ideal, was doomed.
She hadn't bought into the warnings that Lisbon would make abortion freely available on every street corner or that José Manuel Barroso was coming to conscript my nephew into a European army. Nor did she suspect it would impose mandatory euthanasia for the over 70s as the wilder scare stories had suggested.
Enough doubt had been planted in her mind however of possible risks and dangers. And nobody who advocated support for the treaty seemed capable of identifying a single benefit.
Shocked EU leaders can take some comfort from knowing why the Irish bit the hand that fed them. Most people couldn't understand the document. They were urged to trust the political establishment. But trust was in short supply with top government figures up to their necks in sleaze inquiries. Confusion left the debate open to hijacking by extremists. Fears about the economy, and about immigration, played their part. And Gay Byrne (a sort of Irish Jeremy Clarkson) said he was voting "no".
And the Irish no longer care if they are accused of ingratitude by their former benefactors. That so much of the confidence derives from EU membership is the irony.
Political leaders will have to address the disconnect between what they think the project is about and how they sell it. It's too late to win over the British, but leaders must soothe the fears that, however irrationally, have become planted, even in the minds of those who once unquestioningly signed up to the European dream. Ordinary people, like my mother.
Katherine Butler is foreign editor of The Independent