In Homer's The Odyssey, brave Ulysses tested the Sirens, sea monsters whose beautiful singing lured sailors to their deaths. He had his crew block their ears, and they tied him to a mast so he could hear the enchanting song. The ship survived, though Ulysses nearly went mad.

A modern-day Liberal Ulysses has found himself attracted to Canada's constitutional Siren song. Michael Ignatieff is willing to reopen the document to get Quebec's signature. If Quebec signs on to the constitution, the argument goes, the problem of national unity will be solved. A historian who sees the big picture, Mr. Ignatieff is attracted to the idea of making Canada whole, of bringing to fruition a process begun by another intellectual, Pierre Trudeau.
Mr. Ignatieff sees a certain symmetry, and a legacy waiting to be fulfilled.
Other public figures, too, are musing aloud about reforms that come perilously close to calling for constitutional change. Prime Minister Stephen Harper talks about reforming the Senate, while Quebec Premier Jean Charest is talking not just about the Senate but fiscal imbalance and equalization.

Perhaps it's possible to fix the Senate and address equalization without cracking open the Constitution and spilling its innards all over the Canadian Shield. But trying to bring Quebec into the fold is like going in for major surgery, with the risk being that behind the mask is another Jacques Parizeau. The effort to save the patient ends up killing him.

Yes, it would be wonderful to have Quebec sign on. Constitutions are important documents. In modern democracies, constitutions articulate the shared civic creed of the citizenry. It is important, practically and symbolically, for a federation to have all parties represented in these central documents.
But those gains, practical and symbolic, must be weighed against the risks. The national temperature rises during constitutional talks. Failures, such as the Meech Lake and Charlottetown accords, were devastating and nearly fatal.
When sovereigntists discuss the timing of another referendum on Quebec secession, they refer to "winning conditions." The time to hold a referendum, they say, will be defined as the moment when a "Yes" victory can be obtained. They know that a third loss could put the idea of Quebec independence on a back-burner for another generation.

Such a calculation should also govern federalists on constitutional reform. We will only be able to amend that document when there is a weighty consensus inside and outside Quebec.

That consensus is not immediately apparent today, nor is it obvious on the horizon.

Besides, Quebec's signature won't kill the separatist virus. It would soften the humiliation of the 1982 patriation and make it harder to argue that Canada rejects Quebec, but ideological separatists will still long for an independent country.

Ultimately, Quebecers' attachment to Canada is ensured by prosperity for all and competent, clean government. That is what we need today, not more constitutional agony.