You didn't have to spend long yesterday in Jerusalem's Mahane Yehuda market to appreciate the mythic status of Ariel Sharon in the Israeli popular imagination. Maybe it's because he's the last of the generals whose career predates the state itself. Maybe it's because despite presiding as Prime Minister over - and many would say helping to trigger - four years of bloody armed conflict, "he made us feel secure", as one stallholder said. But the anxiety was genuine, the uncertainty about who ought to replace him palpable.
For once "political vacuum" is more than a cliché. Yeats' famous line "things fall apart, the centre cannot hold" has a strangely powerful resonance for the Israeli public as it wakes up to the realisation that the Prime Minister on whom its majority had uncritically relied for the past five years is no longer there to lead them.
After Ariel Sharon's first stroke, there was intense debate in the Israeli media about what would happen, if he were suddenly to disappear from political life, to Kadima, the party he founded in November 2005.
The conventional wisdom was that Kadima was nothing without Sharon, that it was simply a personal vehicle for the man who remained, for complex reasons, the most popular politician in Israel and that in his absence it would implode as its supporters, and some of its leading personalities, reverted to their original ideological homes.
That scenario, moreover, was almost certainly better for the right than for the left. Since most of the support for Kadima had come from Likud, it would be likeliest to return there. This may yet happen. Netanyahu, the man who opportunistically resigned at the moment calculated to burnish his credentials with the extreme right, will do everything he can to lure back those who defected with Sharon.
But the view that Kadima will necessarily collapse without Sharon may be based on a misunderstanding of what has happened to majority Israeli public opinion since the Oslo accords. It was hard yesterday to find a single Mahane Yehuda stallholder prepared to condemn the withdrawal from Gaza.
This would be less surprising if the market hadn't always been a hard-right bastion, exactly the sort of working-class traditionally Likud stronghold where the party's doctrine of an Israel stretching from the Jordan to the Mediterranean was taken literally. If Sharon was going to enact withdrawals from the West Bank, you couldn't help feeling these once fundamentalist Likudniks would have backed him.
They have not, of course, suddenly became peaceniks. Indeed, one of the attractions of Sharon was precisely that he reflected - as well as stimulated - their belief that Arafat was too malign, and then Mahmoud Abbas too weak, to be a credible partner. If it achieved nothing else Oslo buried for much of mainstream Israeli opinion the idea of a "Greater Israel" running from the river to the sea. But its collapse also hardened hearts against a negotiated, as opposed to a limited and unilateral, withdrawal from the occupied territories.
The Truman Institute has just published polling which shows that nearly two thirds of Israeli electors would still countenance a final status settlement broadly on the lines of the Geneva initiativedrawn up jointly by the Yahad Meretz leader Yossi Beilin and the Palestinian Yasser Abed Rabbo. The proviso was that there had to be credible negotiations which would stick.
It was because they thought there wasn't a hope of that, believing neither in a Greater Israel nor in another Camp David, they gathered for warmth round what Ron Pundak, director of the Peres Centre for Peace, calls the "tribal fire". And that essentially unideological organism was embodied for them in the person of Ariel Sharon. The point is that Sharon did not bring the public into the centre; rather the public brought him. And if that is the case, it is a distinct possibility that the centre could hold without him under Ehud Olmert.
But there is a paradox here. Although Olmert used to be a serious Likud hawk he has been much less so of late. Some, like Pundak, believe his private views - ones which he would never admit in public ahead of an election - may even be broadly in line with that majority in the Truman poll. This was surely not the view of Sharon, who showed every sign of believing that withdrawal for the West Bank should be the minimum required to ensure a Jewish majority in the territory under Israeli control - a minimum guaranteed to be unacceptable to any Palestinian negotiator.
But if Olmert or another centrist has the will, could they have the power? Sharon was forced to use every bit of his political skill, of his credibility with the right as the architect of colonising the West Bank, and of his authority as the man, after Rabin, whose military and political life was most intertwined with the history of the state to achieve the withdrawal - numerically trifling when set against the West Bank settlements - in Gaza. In doing so he set a momentous precedent. But that is not itself enough to ensure that someone else could pull off the same in the West Bank in what would have been his third term.
But it is a near certainty that it won't happen if the centre does not hold. The Israeli novelist A B Yehoshua wrote a piece in Haaretz recently making an incontestable case for Israelis to vote for Amir Peretz, the one party leader truly committed to final status negotiations with the Palestinians. He was particularly scornful of Shimon Peres for leaving Labour allegedly to pursue the "peace agenda", arguing that his defection undermined Peretz's pursuit of social justice and that everyone knew Labour would support any moves to withdraw from the West Bank anyway.
Yehoshua is right. A Labour landslide, moreover, would open up new and extraordinarily hopeful possibilities. But the signs are that this is not going to happen. Which means that the best hope is a centre and left majority in the Knesset. And that requires, if only for this election, for Kadima to hold together as well as for Labour to succeed. For the alternative is much darker, a coalition government, perhaps led by Netanyahu, the settlers' champion, between Likud and a badly weakened centre party. A scenario in which, as in the last lines of that same Yeats verse, "the best lack all conviction while the worst/Are full of passionate intensity".