Is it stupid for the EU debate to focus on the economy?
Do you remember Barbara Castle and her shopping trip to Brussels?
The Labour cabinet minister was a star of the "out" campaign in the referendum in 1975.
Although long-departed to the great debating chamber in the sky, she may be inspiring this referendum - but the other side rather than her own.
What wins elections?
Mrs Castle believed that if voters were shown they would be worse off, if Britain stayed in the then European Economic Community (EEC), they would vote to leave.
Of course, the mere fact we are due to have another referendum 40 years later suggests Mrs Castle's strategy didn't work.
There is a photograph of Mrs Castle, her great niece and the wife of a Conservative MP, posing at a news conference with the things they had bought, with prices displayed to demonstrate they were cheaper in Britain than on the continent.
I understand that the public relations team offering advice to the campaign to stay in the EU this time has devised a campaign largely based on economics.
Doubtless comparative shopping will figure at some point, too.
The potential risks of this approach were brought home to me when I chaired a debate about Brexit a few days ago in front of 400 lawyers.
Six panellists representing the two sides lectured, argued and debated in the Victorian splendour of Lincoln's Inn, London, one of the places the legal establishment of England and Wales calls home.
Trade and economics were raised.
And the "In" side were frustrated by the insistence of those who want to leave that it wasn't their job to say what relationship the UK should negotiate with the EU once outside of it.
But what the "Out" side appeared to have was a more clearly communicated argument about identity, and a sense of belonging or not belonging.
Chatting to people in the audience afterwards (random encounters with a self-selecting group, of course) it was clear that such messages made more of an impact than the blizzard of statistics.
Time to decide
You may think both sides have plenty of time to polish their message, but I suspect not.
Both sides think the EU Summit, which concludes on Friday, will finalise the changes David Cameron is negotiating - even if there are a few fireworks and some stage smoke on the way.
The referendum legislation requires a 10-week campaign period. However, David Cameron promised a six-week period prior to that for discussion and finalising matters.
A senior source in Vote Leave, with connections to Downing Street, told me that David Cameron always intended to hold the referendum on 23 June, and their plans are based on him doing so.
That may be 18 weeks away, but in truth the campaign begins the moment that Donald Tusk, the President of the Council and in effect EU lead negotiator, emerges with Mr Cameron to declare the deal has been done.
At that point, wherever they are, British cabinet ministers will be besieged by journalists and will no longer be able to avoid the question: is the deal enough or not enough to stay in the EU?
As one politician put it to me gleefully, it will be "the moment when I can denounce the Prime Minister".
Even if the "In" campaign find economics no more useful for them than it was for Barbara Castle and the "Out" side 40 years ago, it still has weapons it thinks could make a difference.
One is Sir John Major.
I am told he is saving his intervention for a moment when he judges it will have maximum impact.
Few in Westminster would be surprised if this instinctively loyal man does anything other than urge voters to support the Prime Minister by voting to remain in the EU.
There is one other, far more contentious issue: the impact of Brexit on Northern Ireland.
It is the only part of the UK which has a land border with another EU country.
Anglo-Irish co-operation at governmental level has played a significant part in sustaining the Northern Ireland agreement to end sectarian violence.
Some on the "In" side think the UK's departure from the EU could have a de-stabilising effect, especially if the Unionist parties accepted Brexit and the nationalists and republicans did not.
The "Out" campaigners think this is part of what they call "project fear", exaggerating the risks of quitting the EU.
And some think it downright offensive to imply that Northern Ireland could be less peaceful outside the EU.
But before the campaign begins, a word of caution for both sides.
When, at the end of the debate at Lincoln's Inn, I asked if anyone in the audience had changed their mind as a result of the preceding 90 minutes, just one of the 400-strong audience raised his hand.
Both sides have a lot more work to do if opinion is to shift decisively in their favour.
Shaun Ley chaired the debate "EU - Should we stay or should we go?" at Brick Court Chambers. You can download the debate here.
Further reading on the UK's EU referendum
EU renegotiation: Did Cameron get what he wanted?
Referendum timeline: What will happen when?
The view from Europe: What's in it for the others?